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J. CETACEAN RES. MANAGE. 11(1):31–40, 2009 31 J.J. CETACEAN CETACEANCETACEAN RES. RES. MANAGE. MANAGE. MANAGE.11(1):31–40, 11(1):31–11(1):31–40,40,­­ 2009 2010 2009 3131

SeasonalSeasonal estimates estimates of of densities densities and and predation predation rates rates of of cetaceans cetaceans inin the the Ligurian Ligurian Sea, Sea, northwestern northwestern Mediterranean Mediterranean Sea: Sea: an an initial initial examinationexamination SOPHIE LARAN*,+,CLAUDE JOIRIS+,ALEXANDRE GANNIER# AND ROBERT D. KENNEY^ SOPHIESOPHIELARANLARAN*,+*,+,C,CLAUDELAUDEJOIRISJOIRIS+,A+,ALEXANDRELEXANDREGGANNIERANNIER# AND# ANDROBERTROBERTD.D. K KENNEYENNEY^ ^ ContactContact e-mail: e-mail: [email protected] [email protected] ABSTRACT ABSTRACTABSTRACT The Ligurian Sea is one of the most attractive areas for cetaceans in the Mediterranean Sea, and is now included in a Marine Protected Area, the TheThe Ligurian Ligurian Sea Sea is isone one of of the the most most attractive attractive areas areas for for cetaceans cetaceans in in the the Mediterranean Mediterranean Sea, Sea, and and is isnow now included included in in a Marine a Marine Protected Protected Area, Area, the the Pelagos Sanctuary. Despite a lower species diversity than in other parts of the world, because of their abundance, cetaceans are thought to represent PelagosPelagos Sanctuary. Sanctuary. Despite Despite a lower a lower species species diversity diversity than than in inother other parts parts of of the the world, world, because because of of their their abundance, abundance, cetaceans cetaceans are are thought thought to torepresent represent significant consumers in this ecosystem. Surveys were conducted within the Pelagos Sanctuary from 2001 to 2004. Densities of five species: significantsignificant consumers consumers in in this this ecosystem. ecosystem. Surveys Surveys were were conducted conducted within within the the Pelagos Pelagos Sanctuary Sanctuary from from 2001 2001 to to 2004. 2004. Densities Densities of of five five species: species: striped dolphin ( ); fin whale ( ); sperm whale ( ); long-finned pilot whale stripedstriped dolphin dolphin ( (Stenella coeruleoalba);); fin fin whale whale ( (Balaenoptera physalus);); sperm sperm whale whale ( (Physeter macrocephalus);); long-finned long-finned pilot pilot whale whale ( StenellaStenella); and coeruleoalba coeruleoalba Risso’s dolphin ( BalaenopteraBalaenoptera), were physalus physalus estimated and convertedPhyseter toPhyseter biomass. macrocephalus macrocephalus Total biomass density of cetaceans in the ( (Globicephala melas); and); and Risso’s Risso’s dolphin dolphin ( (Grampus griseus), were), were estimated estimated and and converted converted to to biomass. biomass. Total Total biomass biomass density density of of cetaceans cetaceans in in the the GlobicephalaLigurianGlobicephala Sea melas was melas estimated as 93kg km-2Grampus(CV=28%)Grampus griseusgriseus in winter (October to March) and 509kg km-2 (CV=16%) in summer (April to September). LigurianLigurian Sea Sea was was estimated estimated as as 93kg 93kg km km-2-2 (CV=28%)-2 (CV=28%) in in winter winter (October (October to to March) March) and and 509kg 509kg km km-2-2 -2(CV=16%)(CV=16%) in in summer summer (April (April to to September). September). Daily predation rates by cetaceans were estimated as 2.9kg km-2 d-1 in winter, increasing to 10.4kg km-2 d-1 in summer, corresponding to a total DailyDaily predation predation rates rates by by cetaceans cetaceans were were estimated estimated as as 2.9kg 2.9kg km km-2-2 -2d-1-1d-1inin winter, winter, increasing increasing to to 10.4kg 10.4kg km km-2-2 -2d-1-1d-1inin summer, summer, corresponding corresponding to to a total a total annual ingestion of 2.4t km-2 y-1. The annual primary production required for cetaceans was estimated to be 12.6gC m-2 y-1, corresponding to 6- annualannual ingestion ingestion of of 2.4t 2.4t km km-2-2 -2y-1-1y..-1 The The. The annual annual annual primary primary primary production production production required required required for for for cetaceans cetaceans cetaceans was was was estimated estimated estimated to to to be be be 12.6gC 12.6gC 12.6gC m m-2-2 m-2y-1-1y,,-1 corresponding corresponding, corresponding to to to 6- 6- 6- 15% of the net primary production known for this area. Estimated cetacean predation on fish was similar to reported fisheries landings, 15%15% of of the the net net primary primary production production known known for for this this area. area. Estimated Estimated cetacean cetacean predation predation on on fish fish was was similar similar to to reported reported fisheries fisheries landings, landings, nevertheless, management of artisanal fisheries and accurate quantification of the resources they exploit will be necessary for the responsible nevertheless,nevertheless, management management of of artisanal artisanal fisheries fisheries and and accurate accurate quantification quantification of of the the resources resources they they exploit exploit will will be be necessary necessary for for the the responsible responsible management of fisheries in this Mediterranean Marine Protected Area. managementmanagement of of fisheries fisheries in in this this Mediterranean Mediterranean Marine Marine Protected Protected Area. Area.

KEYWORDS: INDEX OF ABUNDANCE; NUTRITION; FOOD/PREY; SANCTUARIES; FEEDING GROUNDS; SURVEY- VESSEL; KEYWORDS:KEYWORDS: INDEX INDEX OF OF ABUNDANCE; ABUNDANCE; NUTRITION; NUTRITION; FOOD/PREY; FOOD/PREY; FOOD/PREY; SANCTUARIES; SANCTUARIES; SANCTUARIES; FEEDING FEEDING FEEDING GROUNDS; GROUNDS; GROUNDS; SURVEY- SURVEY SURVEY- VESSEL; - VESSEL; VESSEL; SURVEY – ACOUSTIC; STRIPED DOLPHIN; FIN WHALE; SPERM WHALE; LONG-FINNED PILOT WHALE; RISSO’S DOLPHIN; SURVEYSURVEY – ACOUSTIC; – ACOUSTIC; STRIPED STRIPED DOLPHIN; DOLPHIN; FIN FIN WHALE; WHALE; SPERM SPERM WHALE; WHALE; LONG-FINNED LONG-FINNED PILOT PILOT WHALE; WHALE; RISSO’S RISSO’S DOLPHIN; DOLPHIN; SURVEYMEDITERRANEAN – ACOUSTIC; SEA; STRIPED NORTHERN DOLPHIN; HEMISPHERE FIN WHALE; SPERM WHALE; LONG-FINNED PILOT WHALE; RISSO’S DOLPHIN; MEDITERRANEANMEDITERRANEAN SEA; SEA; NORTHERN NORTHERN HEMISPHERE HEMISPHERE

addition, six other species are known to inhabit this area: INTRODUCTIONINTRODUCTION addition,addition, six six other other species species are are known known to to inhabit inhabit this this area: area: INTRODUCTIONMarineINTRODUCTION mammals often play key roles within marine sperm whales ( ); Cuvier’s beaked MarineMarine mammals mammals often often play play key key roles roles within within marine marine spermsperm whales whales (Physeter (Physeter macrocephalus macrocephalus);); Cuvier’s Cuvier’s beaked beaked ecosystems, consequently their abundance and their whales ( PhyseterPhyseter macrocephalus macrocephalus); long-finned pilot whales ecosystems,ecosystems, consequently consequently their their abundance abundance and and their their whaleswhales (Ziphius (Ziphius cavirostris cavirostris);); long-finned long-finned pilot pilot whales whales distribution can have important effects on the structure and ( ZiphiusZiphius cavirostris cavirostris); Risso’s dolphins ( ); distributiondistribution can can have have important important effects effects on on the the structure structure and and (Globicephala(Globicephala melas melas);); Risso’s Risso’s dolphins dolphins (Grampus (Grampus griseus griseus); ); function of some ecosystems (Bowen, 1997; Estes , GlobicephalabottlenoseGlobicephala dolphins melas melas ( Grampus);Grampus and more griseus griseus rarely functionfunction of of some some ecosystems ecosystems (Bowen, (Bowen, 1997; 1997; Estes Estesetet al. al., , bottlenosebottlenose dolphins dolphins (Tursiops (Tursiops truncatus truncatus);); and and more more rarely rarely 2006). Nevertheless their role as top predators needsetet to al. al. be short-beaked commonTursiopsTursiops dolphins truncatus (truncatus ). Summer 2006).2006). Nevertheless Nevertheless their their role role as as top top predators predators needs needs to to be be short-beakedshort-beaked common common dolphins dolphins (Delphinus (Delphinus delphis delphis).). Summer Summer characterisedcharacterised and and quantified quantified in in order order to to better better understand understand densitiesdensities have have previously previously been been reported reported for for striped striped dolphins dolphins theirtheir habitat habitat use use and and identify identify the the possible possible impacts impacts of of human human (Forcada(Forcada and and Hammond, Hammond, 1998; 1998; Gannier, Gannier, 1998) 1998) and and fin fin whales whales activities. All cetaceans are carnivores and in many marine (Forcada , 1996; Gannier, 1997), however those for other activities.activities. All All cetaceans cetaceans are are carnivores carnivores and and in in many many marine marine (Forcada(Forcadaetet al. al., 1996;, 1996; Gannier, Gannier, 1997), 1997), however however those those for for other other ecosystemsecosystems they they are are among among the the top top predators predators (Bowen, (Bowen, 1997; 1997; speciesspecies and and seasons seasons have have not not been been published published yet. yet. Trites,Trites, 2002). 2002). Their Their diet diet includes includes a a wide wide variety variety of of prey prey ForFor the the Mediterranean Mediterranean Sea, Sea, the the only only previous previous estimates estimates of of speciesspecies from from small small crustaceans crustaceans up up to to large large squid squid (Barros (Barros and and cetaceancetacean prey prey consumption consumption were were by by Viale Viale (1985). (1985). This This Clarke,Clarke, 2002). 2002). They They have have a fewa few predators predators of of their their own; own; these these authorauthor estimated estimated roughly roughly the the number number of of individuals individuals for for includeinclude large large sharks, sharks, a smalla small number number of of other other cetaceans cetaceans and and northnorth of of 40°N 40°N latitude latitude from from opportunistic opportunistic surveys surveys conducted conducted humans.humans. Given Given their their large large body body sizes sizes and and relatively relatively high high onon oceanographic oceanographic vessels vessels between between 1972 1972 and and 1982. 1982. It It was was metabolicmetabolic rates, rates, cetaceans cetaceans can can represent represent significant significant assumedassumed that that strip strip transect transect methodology methodology could could be be consumersconsumers in in marine marine ecosystems. ecosystems. consideredconsidered and and the the effective effective strip strip half-width half-width used used was was taken taken ConcernsConcerns about about the the interactions interactions of of fisheries fisheries with with marine marine fromfrom other other studies. studies. With With additional additional survey survey data data to to allow allow mammals in the Mediterranean Sea are probably as old as the estimation of cetacean densities throughout the year, better mammalsmammals in in the the Mediterranean Mediterranean Sea Sea are are probably probably as as old old as as the the estimationestimation of of of cetacean cetacean cetacean densities densities densities throughoutthroughout throughout the the year, year, year, accurate better better firstfirst human human attempts attempts to to catch catch fish fish with with a neta net (Bearzi, (Bearzi, 2002). 2002). In In estimatesestimates of of consumption consumption rates rates are are now now possible. possible. thethe Mediterranean, Mediterranean, most most commercial commercial fish fish stocks stocks are are considered considered AA single-species single-species approach approach to to estimating estimating consumption consumption rates rates overexploited (Farrugio , 1993). This adds some degree of or trophic relationships beginning from population size has a overexploitedoverexploited (Farrugio (Farrugioetet al. al., 1993)., 1993). This This adds adds some some degree degree of of oror trophic trophic relationships relationships beginning beginning from from population population size size has has a a urgencyurgency to to a a need need for for estimates estimates of of cetacean cetacean consumption. consumption. numbernumber of of limitations limitations when when dealing dealing with with multiple multiple species, species, CetaceansCetaceans may may be be affected affected by by fisheries fisheries even even when when their their prey prey especiallyespecially in in terms terms of of ecological ecological requirements requirements of of species species that that speciesspecies are are not not target target species species of of commercial commercial fisheries fisheries because because of of varyvary widely widely in in body body size. size. In In this this paper, paper, an an attempt attempt was was made made linkages though the food web (Trites , 1997). In addition, to estimate annual prey consumption rates by cetaceans in linkageslinkages though though the the food food web web (Trites (Tritesetet al. al., 1997)., 1997). In In addition, addition, toto estimate estimate annual annual prey prey consumption consumption rates rates by by cetaceans cetaceans in in sincesince 2002, 2002, the the Ligurian Ligurian Sea, Sea, located located in in the the northwestern northwestern thethe Ligurian Ligurian Sea, Sea, and and their their overall overall trophic trophic impacts impacts as as MediterraneanMediterranean Sea, Sea, has has been been designated designated as as a Marinea Marine Protected Protected measuredmeasured by by primary primary production production required required to to support support that that AreaArea (MPA), (MPA), called called the the Pelagos Pelagos Sanctuary Sanctuary (Fig. (Fig. 1). 1). consumption.consumption. It It has has been been assumed assumed that that cetaceans cetaceans use use the the InIn summer, summer, the the Ligurian Ligurian Sea Sea attracts attracts large large numbers numbers of of habitathabitat for for feeding feeding purposes, purposes, as as for for the the majority majority of of species, species, cetaceans (Forcada , 1996; Forcada and Hammond, feeding activity was observed or acoustically verified several cetaceanscetaceans (Forcada (Forcadaetet al. al.,, 1996; 1996; Forcada Forcada and and Hammond, Hammond, feedingfeeding activity activity was was observed observed or or acoustically acoustically verified verified several several 1998; Gannier, 2005),etet al. in al. particular striped dolphins ( times during surveys, except for pilot whales, which are 1998;1998; Gannier, Gannier, 2005), 2005), in in particular particular striped striped dolphins dolphins (Stenella (Stenella timestimes during during surveys, surveys, except except for for pilot pilot whales, whales, which which are are ) and fin whales ( StenellaStenella) In known to feed at night (Baird , 2002). coeruleoalbacoeruleoalba)) and and fin fin whales whales (Balaenoptera (Balaenoptera physalus physalus). )In. In knownknown to to feed feed at at night night (Baird (Bairdetet al. al., 2002)., 2002).

* Centre de Recherche sur les Cétacés, Marineland-Parques Reunidos, 306 av Mozart, 06600 Antibes, France. * Centre* Centre de de Recherche Recherche sur sur les les Cétacés, Cétacés, Marineland-Parques Marineland-Parques Reunidos, Reunidos, 306 306 av av Mozart, Mozart, 06600 06600 Antibes, Antibes, France. France. + Laboratory for Polar Ecology (PolE), rue du Fodia 18, B-1367 Ramillies, Belgium. ++ Laboratory Laboratory for for Polar Polar Ecology Ecology (PolE), (PolE), rue rue du du Fodia Fodia 18, 18, B-1367 B-1367 Ramillies, Ramillies, Belgium. Belgium. # Groupe de Recherche sur les Cétacés, BP 715, 06633 Antibes, France. # Groupe# Groupe de de Recherche Recherche sur sur les les Cétacés, Cétacés, BP BP 715, 715, 06633 06633 Antibes, Antibes, France. France. ^ Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, USA. ^ Graduate^ Graduate School School of of Oceanography, Oceanography, University University of of Rhode Rhode Island, Island, Narragansett, Narragansett, Rhode Rhode Island Island 02882, 02882, USA. USA. 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 32 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 32

32 LARAN et al.:.: SEASONAL ESTIMATESESTIMATES OFOF CETACEANSCETACEANS ININ THE THE LIGURUIAN LIGURIAN SEA 32 LARAN et al.: SEASONAL ESTIMATES OF CETACEANS IN THE LIGURUIAN SEA

Fig. 1. Study area with transect locations (black and grey lines), PELAGOS Sanctuary borders (dashed lines) and Sardinia area (FAO). Fig. 1. Study area with transect locations (black and grey lines), PELAGOS Sanctuary borders (dashed lines) and Sardinia area (FAO).

within the same general area in the sanctuary (Gannier, MATERIALS AND METHODS within the same general area in the sanctuary (Gannier, MATERIALS AND METHODS 2006) (Fig. 1). All surveys were conducted with the same The Ligurian Sea is located north of the western 2006) (Fig. 1). All surveys were conducted with the same The Ligurian Sea is located north of the western dedicated platform, a 13m vessel powered by two 350HP Mediterranean basin (Fig. 1). This region includes large areas dedicated platform, a 13m vessel powered by two 350HP Mediterranean basin (Fig. 1). This region includes large areas inboard engines, and a consistent crew. Three experienced of deep water (>2,000m), with a narrow continental shelf. It inboard engines, and a consistent crew. Three experienced of deep water (>2,000m), with a narrow continental shelf. It observers, seated with their eyes 4m above the water is characterised by a frontal system, which provides a high observers, seated with their eyes 4m above the water is characterised by a frontal system, which provides a high surface, searched the forward sector (-90° to +90° relative to level of primary production, peaking in March-April (Jacques surface, searched the forward sector (-90° to +90° relative to level of primary production, peaking in March-April (Jacques the bow) with the naked eye and were rotated every hour , 1973; Nival , 1975). The Pelagos Sanctuary the bow) with the naked eye and were rotated every hour et al., 1973; Nival et al., 1975). The Pelagos Sanctuary (see Laran and Drouot-Dulau, 2007). etincludes al. 87,500km2, butet al. the estimates used in this study only (see Laran and Drouot-Dulau, 2007). includes 87,500km2, but the estimates used in this study only The survey data were grouped by six-month seasons pertain to the northernmost portion (Fig. 1). In the absence of The survey data were grouped by six-month seasons pertain to the northernmost portion (Fig. 1). In the absence of across the three years of sampling and analysed applying seasonal surveys of the whole MPA, cetacean density was across the three years of sampling and analysed applying seasonal surveys of the whole MPA, cetacean density was standard line-transect methods (Buckland , 2001). estimated from transects conducted only in its northern part. standard line-transect methods (Buckland et al., 2001). estimated from transects conducted only in its northern part. Transects selected for analysis varied fromet 10 al. to 158km It must be noted that environmental conditions in the corridor Transects selected for analysis varied from 10 to 158km It must be noted that environmental conditions in the corridor (mean=81.7km) depending the length of segment conducted do not represent those of the entire MPA and that some (mean=81.7km) depending the length of segment conducted do not represent those of the entire MPA and that some with good sighting conditions. The effective strip half-width cetaceans (e.g. fin whales) are known to aggregate near the with good sighting conditions. The effective strip half-width cetaceans (e.g. fin whales) are known to aggregate near the ( ) was estimated for each species using northern frontal region in summer. Nevertheless it was (esw) was estimated for each species using Distance 5.0 northern frontal region in summer. Nevertheless it was (Thomasesw , 2006); as the numbers of sightingsDistance were 5.0too considered that even rough estimates of biomass, densities (Thomas et al., 2006); as the numbers of sightings were too considered that even rough estimates of biomass, densities low to reliablyet al. estimate for Risso’s dolphins and pilot and predation could be useful in term of management. For all low to reliably estimate esw for Risso’s dolphins and pilot and predation could be useful in term of management. For all whales, additional detectionsesw of the same species, recorded estimates, the year was divided into two equal periods, April- whales, additional detections of the same species, recorded estimates, the year was divided into two equal periods, April- in the northwestern Mediterranean Sea from the same September and October-March, which are referred to as in the northwestern Mediterranean Sea from the same September and October-March, which are referred to as platform were included. For fin whales and striped dolphins, ‘summer’ and ‘winter’ respectively, for convenience. platform were included. For fin whales and striped dolphins, ‘summer’ and ‘winter’ respectively, for convenience. sightings were truncated prior to analysis to exclude 5% of sightings were truncated prior to analysis to exclude 5% of the groups detected at the largest distances following the groups detected at the largest distances following Density estimates Buckland (2001). The density of species during DensityData were estimates collected between February 2001 and February Buckland et al. (2001). The density of species i during Data were collected between February 2001 and February period (inet individuals al. per km2) was estimated by:i 2004 from 30 dedicated line-transect surveys, conducted period j (in individuals per km2) was estimated by: 2004 from 30 dedicated line-transect surveys, conducted j monthly along the same 160km track between the French monthly along the same 160km track between the French mainland and Corsica (Fig. 1) and part of the return transect. mainland and Corsica (Fig. 1) and part of the return transect. The standard sampling design was to survey from France to (1) The standard sampling design was to survey from France to (1) Corsica at a speed of about 22km h-1 (12knots). In this Corsica at a speed of about 22km h-1 (12knots). In this where s is the mean school size of species i during period j; analysis only effort conducted between 18km h-1 and 23km where sij is the mean school size of species i during period j; analysis only effort conducted between 18km-1 h-1 and 23km-1 where sij is the mean school size of species i during period j; analysis-1 only only effort effort conducted conducted between between 18km 18km h h andand 23km 23km h n is the number of primary sightings (after truncation) of h-1 under sea conditions of Beaufort 3 or lower was nij is the number of primary sightings (after truncation) of h-1 under sea conditions of Beaufort 3 or lower was speciesij i during period j and L is the total transect length (km) underconsidered. sea Theconditions return trip of Beaufort on the next 3 dayor lower followed was a species i during period j and Lj is the total transect length (km) considered. The return trip on the next day followed a surveyedi during periodj . TheLj variance of was estimated parallel transect offset 11km north-east from the southbound surveyed during period j. The variance of D was estimated parallel transect offset 11km north-east from the southbound using , byj the delta method (BucklandD , track. A shorter (74km) section of the northbound transect using Distance 5.0, by the delta method (Buckland et al., track. A shorter (74km) section of the northbound transect 2001).Distance Replicate 5.0 transects weighted by transect lengthet were al. was surveyed at lower speeds (13km h-1) to try to estimate 2001). Replicate transects weighted by transect length were was surveyed at lower speeds (13km h-1) to try to estimate considered to estimate var(n). The annual variance or groups the probability of seeing a whale on the trackline, (0), for considered to estimate var(n).n The annual variance or groups the probability of seeing a whale on the trackline, g(0), for of species variances were estimated as the sum of variances of the most common species. Only sections of the northboundg of species variances were estimated as the sum of variances of the most common species. Only sections of the northbound the different components (Buckland et al., 2001). transect conducted at 18-23km h-1, before and after the the different components (Buckland et al., 2001). transect conducted at 18-23km h-1, before and after the For sperm whales, a strip-transectet method al. was applied to lower-speed segment, were included in the analysis. There For sperm whales, a strip-transect method was applied to lower-speed segment, were included in the analysis. There combined visual and acoustic detections. Two-minute was one additional survey conducted in summer 2001 combined visual and acoustic detections. Two-minute was one additional survey conducted in summer 2001 recording sessions (with the vessel propeller de-clutched) recording sessions (with the vessel propeller de-clutched) 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 33 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 33 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 33

J. CETACEAN RES. MANAGE. 11(1):31–40, 2009 33 J. CETACEANCETACEAN RES. MANAGE. MANAGE. 11(1):31–11(1):31–40,40,­­ 2010 2009 33 were performed, each 18.5km of theJ. southbound CETACEAN transect, RES. MANAGE.Kenney11(1):31–40,et al. (1997) 2009 modified that model by adjusting the33 were performed, each 18.5km of the southbound transect, Kenney . (1997) modified that model by adjusting the withwere a performed, monaural hydrophoneeach 18.5km (Magrec, of the southbound HP 60MT). transect, As the multiplierTritesKenney etet al slightly al. . (1997) (1997) downward modified modified in thatthat an model attempt model by to by adjusting account adjusting thefor the exactwith a number monaural of hydrophonewhales could (Magrec, not be reliably HP 60MT). determined As the themultiplier differenceet slightly al between downward ingestion in an for attempt growth to and account ingestion for exactwith a number monaural of hydrophonewhales could (Magrec, not be reliably HP 60MT). determined As the themultiplier difference slightly between downward ingestion in an for attempt growth to and account ingestion for whenexact more number than of three whales whales could were not vocally be reliably active determinedin the area, forthe maintenance: difference between ingestion for growth and ingestion threewhen wasmore the than maximum three whales school were size vocally allocated active by inthe acoustic area, for maintenance: when more than three whales were vocally active in the area, for maintenance: 0.8 three was the maximum school size allocated by acoustic R2= 0.1 W (3) samplingthree was alone the maximum (Gannier schoolet al., size 2002). allocated Two consecutiveby acoustic = 0.1 0.8 (3) sampling alone (Gannier , 2002). Two consecutive R2= 0.1 W 0.8 (3) positivesampling stations alone or(Gannier a positiveet al.station, 2002). following/preceding Two consecutive a Trites etR2 al. (1997)W used the model of Kleiber (1975) to sightingpositive stations were considered or a positiveet as al.station distinct following/preceding whales when the a estimateKenneyTrites et et basal al. al.(1997) metabolic(1997) used used rate thethe (BMR, modelmodel in ofof kcal KleiberKleiber d-1): (1975)(1975) to positive stations or a positive station following/preceding a Trites et al. (1997) used the model of Kleiber-1 (1975) to recordedsighting click-level were considered index was as equal distinct or greater whales than when 3 (on the a estimate basal metabolic rate (BMR, in kcal d-1): recordedsighting click-level were considered index was as equal distinct or greater whales than when 3 (on the a estimateBMR basal= metabolic 70 W 0.75 rate (BMR, in kcal d ): (4) scalerecorded varying click-level from index 0 to 5; was see equal Laran or greater and Drouot-Dulau, than 3 (on a = 70 0.75 (4) scale varying from 0 to 5; see Laran and Drouot-Dulau, BMR = 70 W 0.75 (4) 2007).scale varying As sperm from whales 0 to 5; do see not Laran usually and produce Drouot-Dulau, regular and thenBMR applied aW scaling factor to account for assimilation clicks2007). at As the sperm surface whales (Drouot doet not al., usually2004), the produce school regular size of efficiencyand then applied and activity: a scaling factor to account for assimilation clicks2007). at As the sperm surface whales (Drouot do not, usually2004), the produce school regular size of efficiencyand then applied and activity: a scaling factor to account for assimilation eachclicks sighting at the surface was (Drouot estimatedet al. by, 2004), combining the school visual size and of efficiency and activity: acousticeach sighting information. was estimated With theet sameal. by combining monaural hydrophone, visual and acousticeach sighting information. was estimated With the same by combining monaural hydrophone, visual and Gannieracousticet information. al. (2002) observed With the asame click-level monaural index hydrophone, of 0 for a (5) spermGannier whaleet al. located (2002) observedat 14.8km a and click-level a level index of 2 at of 9.4km; 0 for a (5) Gannier . (2002) observed a click-level index of 0 for a where is the energy density of the prey consumed,(5) fromsperm their whaleet results al located it is at estimated 14.8km and that a whales level of were 2 at heard 9.4km; up E sperm whale located at 14.8km and a level of 2 at 9.4km; assumedwhere E tois be the 1,000kcal energy density kg-1 for of fish the preyand crustaceans consumed, from to their 13km results away it (see is estimated fig. 3, plot that for whales mono-hydrophone, were heard up in where is the energy density of the prey consumed, from their results it is estimated that whales were heard up (ClarkeassumedE and to be Prince, 1,000kcal 1980; kg Sissenwine-1 for fish and, crustaceans 1984) and Gannierfromto 13km to 13km away. 2002). away (see (see Therefore fig. fig. 3, 3, plot anplot arbitrary for for mono-hydrophone, distance mono-hydrophone, of 13km in in assumed to be 1,000kcal kg-1 for fishet and al. crustaceans from to 13kmet al away (see fig. 3, plot for mono-hydrophone, in (Clarke and-1 Prince, 1980; Sissenwine , 1984) and Gannier . 2002). Therefore an arbitrary distance of 13km 830kcal(Clarke and kg Prince,for squid 1980; (Croxall Sissenwine andet Prince, al., 1984) 1982). and wasGannier assumedet al.to 2002). be acoustically Therefore an scanned arbitrary on distance each side of of 13km the 830kcal kg-1 for squid (Croxall andet Prince, al. 1982). was assumedet al to be acoustically scanned on each side of the Sigurjónsson830kcal kg-1 andfor Víkingsson squid (Croxall (1997) used and Lockyer’s Prince, (1981) 1982). transectwas assumed line (equivalent to be acoustically to esw), scanned considering on each the side detection of the Sigurjónsson and Víkingsson (1997) used Lockyer’s (1981) transect line (equivalent to ), considering the detection modelSigurjónsson for near-basal and Víkingsson metabolic (1997) rate: used Lockyer’s (1981) capabilitytransect line of the (equivalent hydrophone. to esw The), calculation considering of the sperm detection whale model for near-basal metabolic rate: capability of the hydrophone.esw The calculation of sperm whale model for near-basal0.783 metabolic rate: densitycapability was of equivalent the hydrophone. to Eqn. The (1). calculation of sperm whale M = 110 W (6) density was equivalent to Eqn. (1). M = 110 W 0.783 (6) density was equivalent to Eqn. (1). whichM they= 110 thenW scaled0.783 upwards for 80% assimilation(6) Biomass and prey consumption efficiencywhich they and then a 1.5× scaled activity upwards factor. for 80%Incorporating assimilation the Biomass and densities prey consumption for each species were estimated by efficiencywhich they and then a 1.5× scaled activity upwards factor. for 80%Incorporating assimilation the Biomass and densities prey consumption for each species were estimated by energy-to-biomassefficiency and a 1.5×conversion, activity their factor. model Incorporating becomes: the multiplyingBiomass densities calculated for densities each species by average were body estimated mass (W byin energy-to-biomass conversion, their model becomes: multiplying calculated densities by average body mass ( in energy-to-biomass conversion, their model becomes: kg).multiplying The mean calculated body mass densities values, by average for males body and mass females (W in separately,kg). The mean were body taken mass from values,Trites and for Pauly males (1998) and females exceptW separately,kg). The mean were body taken mass from values,Trites and for Pauly males (1998) and females except (7) forseparately, species were where taken independent from Trites evidence and Pauly suggested (1998) except that (7) for species where independent evidence suggested that (7) individualsfor species in where the Mediterranean independent tended evidence to be suggested smaller than that All four models were used to estimate the daily rations of elsewhereindividuals in in the the world. Mediterranean In those tended cases, tomaximum be smaller lengths than cetaceansAll four models ranging were in size used from to estimate 30kg to the 100t daily (i.e. rations harbour of elsewhereindividuals in in the the world. Mediterranean In those tended cases, tomaximum be smaller lengths than cetaceansAll four models ranging were in size used from to estimate 30kg to the 100t daily (i.e. rations harbour of fromelsewhere the Mediterranean in the world. were In those used cases, in the maximumregression modelslengths porpoisecetaceans to ranging blue in whale), size from presuming 30kg to the 100t same (i.e. harbour diet at from Tritesthe Mediterranean and Pauly (1998) were usedto compute in the regression mean weights models for 1,000kcalporpoise to kg-1 blue(Fig. whale), 2). The presuming Sigurjónsson the and same Víkingsson diet at from the Mediterranean were used in the regression models porpoise to-1 blue whale), presuming the same diet at malesfrom Trites and and females. Pauly (1998) Maximum to compute body mean lengths weights for (1997)1,000kcal method kg-1 (Fig. resulted 2). in The the Sigurjónsson highest estimates and Víkingsson across the malesfrom Trites and and females. Pauly (1998) Maximum to compute body mean lengths weights for (1997)1,000kcal method kg (Fig. resulted 2). in The the Sigurjónsson highest estimates and Víkingsson across the Mediterraneanmales and females. specimens Maximum came from body the lengths long-term for entire(1997) range, method and resulted the Trites in theet al. highest(1997) estimates method across generated the strandingMediterranean database specimens and were came provided from by the F. Dhermainlong-term theentire lowest range, values and the at all Trites butet the al. very(1997) largest method body generated weights. strandingMediterranean database specimens and were came provided from by the F. Dhermainlong-term theentire lowest range, values and the at all Trites butet the al. very(1997) largest method body generated weights. (Groupestranding d’Etude database des and Cétacés were de provided Méditerranée) by F. and Dhermain O. Van Thethe lowest Innes et values al. (1987) at alland but the Kenney veryet largest al. (1997) bodymethods weights. Canneyt(Groupe (Centre d’Etude d’Etude de des Recherche des Cétacés Cétacés de sur Méditerranée) les de Mammifères Méditerranée) and Marins). O. Vanand producedThe Innes intermediateet al. (1987) values, and Kenney with theet al. latter(1997) differing methods in Canneyt(Groupe(Centre d’Etude de des Recherche Cétacés de sur Méditerranée) les Mammifères and Marins). O. Van producedThe Innes intermediateet al. (1987) values, and Kenney with theet al. latter(1997) differing methods in ForO.Canneyt Van each Canneyt(Centre species dethe (CRMM Recherche male and - University female sur les Mammifèresmeans of wereLa Rochelle). averaged Marins). slope.produced Barlow intermediateet al. (2008) values, tested with an eventhe latter broader differing range ofin withFor each the sex species ratio theassumed male toand be female 50%, except means for were the averaged strongly consumptionslope. Barlow models,et al. (2008) and settled tested on an theeven same broader one range used by of withFor each the sex species ratio theassumed male andto be female 50%, except means for were the averaged strongly consumptionslope. Barlow models,et al. (2008) and settled tested on an theeven same broader one range used by of dimorphicwith the sex species ratio assumed (sperm whale to be 50%, and pilot except whale), for the where strongly the Kenneyconsumptionet al. models, (1997). and They settled also on concluded the same that one the used same by sexdimorphic ratio was species assumed (sperm to whale be 40% and malepilot whale), and 60% where female the modelKenney usinget al 3.0. (1997). as a multiplier They also rather concluded than 2.5 that (Fig. the 2) same and sexdimorphic ratio was species assumed (sperm to whale be 40% and malepilot whale), and 60% where female the modelKenney usinget al 3.0. (1997). as a multiplier They also rather concluded than 2.5 that (Fig. the 2) same and (followingsex ratio was Barlow assumedet al., to 2008; be 40% Trites male and Pauly, and 60% 1998). female The model using 3.0 as a multiplier rather than 2.5 (Fig. 2) and CV(following of the biomass Barlow et density al., 2008; estimate Trites was and assumed Pauly, 1998). to be The the CV(following of the biomass Barlow et density al., 2008; estimate Trites was and assumed Pauly, 1998). to be The the sameCV of as the that biomass of the corresponding density estimate density, was assumed as no information to be the onsame maximum as that of length the corresponding variability was density, available. as no informationCumulative onsame maximum as that of length the corresponding variability was density, available. as no informationCumulative biomasson maximum densities length for variability all odontocetes was available. and total Cumulative cetaceans werebiomass computed densities by summingfor all odontocetes the estimates and for total the individual cetaceans werebiomass computed densities by summingfor all odontocetes the estimates and for total the individual cetaceans species,were computed and cumulative by summing CV’s the were estimates computed for the by individual summing thespecies, individual and cumulative variances (following CV’s were Buckland computedet by al. summing, 2001). thespecies, individual and cumulative variances (following CV’s were Buckland computed by summing, 2001). theA individual variety of variances methods exist (following for estimating Buckland theet consumption al., 2001). ratesA variety of cetaceans of methods (see review exist for by estimatingLeaper and the Lavigne,et consumption al. 2007). ratesA variety of cetaceans of methods (see review exist for by estimatingLeaper and the Lavigne, consumption 2007). Sergeantrates of cetaceans (1969), extrapolating (see review by from Leaper feeding and Lavigne, rates of captive 2007). odontocetesSergeant (1969), ranging extrapolating in size from from harbour feeding porpoises rates of to captive killer odontocetesSergeant (1969), ranging extrapolating in size from from harbour feeding porpoises rates of to captive killer whales,odontocetes proposed ranging that in feeding size from rates harbour of free-living porpoises cetaceans to killer couldwhales, be proposed computed that as afeeding percentage rates of of body free-living weight, cetaceans ranging couldwhales, be proposed computed that as afeeding percentage rates of of body free-living weight, cetaceans ranging fromcould 3.5-4% be computed in larger as a animals percentage to 10-12%of body weight, in the smallest ranging individuals,from 3.5-4% but in he larger did animals not fit a to mathematical 10-12% in the model. smallest The individuals,from 3.5-4% but in he larger did animals not fit a to mathematical 10-12% in the model. smallest The availableindividuals, mathematical but he did models not fit a are mathematical generally of model. two types: The computingavailable mathematical ingestion rate models as a function are generally of body of twoweight; types: or computingavailable mathematical ingestion rate models as a function are generally of body of twoweight; types: or Fig. 2. Estimates of daily ration (as a percentage of body mass) from computing metabolic ingestion rate rate as a function function of of body body weight weight; and or Fig. 2. Estimates of daily ration (as a percentage of body mass) from scalingcomputing upward metabolic to ingestion rate as rate a function for assimilation of body weight efficiency and Fig.body 2. Estimates mass for cetaceansof daily ration from (as 30kg a percentage (e.g. an average of body male mass) harbour from computing metabolic rate as a function of body weight and Fig.bodyporpoise)body 2. Estimates mass mass to for for 100 cetaceansof daily tonnes ration from (e.g. (as 30kg a bluea percentage (e.g. whale) an average average offrom body four male male mass) different harbour harbour from scaling upward to ingestion rate for assimilation efficiency porpoise) to 100 tonnes (e.g. a blue whale) from four different andscaling activity. upward Innes toet ingestion al. (1987) rate proposed for assimilation that daily efficiency ration (R, models:porpoise)body mass Trites to for 100 et cetaceans al. tonnes (1997) from (e.g. (dotted 30kg a blue line); (e.g. whale) Kenney an average from et al. four male (1997) different harbour (solid and activity.-1 Innes . (1987) proposed that daily ration ( , models:porpoise) Trites to 100et al. tonnes (1997) (e.g. (dotted a blue line); whale) Kenney from et al. four (1997) different (solid inand kg activity. d ) could Innes be estimatedet al. (1987) from proposed body weight that daily (W, in ration kg) by: (R, blackmodels: line); Trites Innes et al. et (1997) al. (1987) (dotted (dashed line); line); Kenney and et Sigurjónsson al. (1997) (solid and in kg d-1) could be estimatedet al from body weight (W, in kg) by:R blackVíkingssonblackmodels: line); line); Trites (1997)Innes Innes et al.et et (alternating (1997) al.al. (1987) (1987) (dottedlong (dashed (dashed line);and short line); line); Kenneydashes). and and et Sigurjónsson Sigurjónsson al. The (1997) solid (solid grey and in kg d-1) could be estimated0.8 from body weight (W, in kg) by: Víkingssonblack line); (1997) Innes (alternating et al. (1987) long (dashed and short line); dashes). and Sigurjónsson The solid grey and R1 = 0.123 W (2) lineVíkingsson represents (1997) the (alternating Kenney et long al. (1997)and short model dashes). using The an solid activity grey 0.8 lineVíkingsson represents (1997) the (alternating Kenney et long al. (1997)and short model dashes). using The an solid activity grey R1 = 0.123 W 0.8 (2) multiplierline represents of 3.0 the instead Kenney of 2.5.et al. (1997) model using an activity R1 = 0.123 W (2) multipliermultiplierline represents of of 3.0 3.0 instead the instead Kenney of of2.5. 2.5.et al. (1997) model using an activity multiplier of 3.0 instead of 2.5. 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 34

34 LARAN et al.: SEASONAL ESTIMATES OF CETACEANS IN THE LIGURUIAN SEA the Innes et al. (1987) model were also plausible. Similarly, This was estimated using a constant transfer efficiency of 10% the Kenney et al. (1997) model has been used for the between successive trophic levels, TL (Pauly and Christensen, 2 -1 principal analyses reported in this paper. 1995). The primary production required (PPRp, gC m y ) to Consumption rates were estimated using Eqns (4) and (5), support consumption of any prey type p was calculated from k and partitioned into three prey categories: fish; cephalopod; consumption of that prey (Qp) using a factor 10 , with k being and zooplankton (crustaceans). In the absence of knowledge the number of trophic steps between phytoplankton (TL = 1) on variation of the ingestion rate, the CVs were propagated and the given prey category: from biomass densities estimates through to the consumption estimates, whilst aware that the CV value would be underestimated by an unknown and maybe (8) important amount. For the group of species, the sum of

variances of the different components were estimated. The where Ep is the energy density of the prey. TL is the trophic estimated percentages of each species’ diet comprising the level of the prey category and assumed to be 2.2 for three categories were based upon previous reviews (Kenney crustaceans, 3.2 for cephalopods, and 3.0 for fish (Pauly and et al., 1985; Kenney et al., 1997; Pauly et al., 1998) as Christensen, 1995). The terms in the denominator converts modified by literature and data specific to the Mediterranean from energy to carbon units (Platt, 1969) and from km2 to Sea. The food of fin whales in summer was assumed to be m2. The primary production required was then compared to 100% crustaceans, as the euphausiid Meganyctiphanes total net primary production as reported in the literature. norvegica is considered as its only food resource (Astruc, 2005; Orsi Relini and Giordano, 1992). Since fin whales are Comparison with fisheries present in the Mediterranean Sea in winter and there is Annual global capture production estimates were extracted evidence of winter feeding, at least close to Sicily (Canese with FishStat Plus1 and the time series of the Food and et al., 2006), no scaling factor was applied to increase Agriculture Organisation of the United Nations (FAO), summer feeding rate to account for winter fasting. Based on available from the area. Results were averaged from 2000 to information for other areas (Lockyer, 2007; Sigurjónsson 2005 for two different areas: (1) the total Mediterranean Sea and Víkingsson, 1997; Viale, 1985), it was assumed that plus Black Sea global dataset of Capture Production (1950- during winter, fin whales feed mainly on euphausiids (90%) 2006); (2) total fishery production (1950-2006) considering but occasionally on fish when available (10%). For sperm commercial, industrial, recreational captures and aquaculture whales, there have been reports on two stomach contents and other kinds of fish farming (FAO, 2008); and (3) the from the Mediterranean Sea (Astruc, 2005; Roberts, 2003); Sardinia region alone (Tyrrhenian Sea to east of Sardinia and both included only cephalopods, mainly Histioteuthis Corsica; Fig. 1) extracted from GFCM (Mediterranean and bonnellii. However, to account for possible consumption of Black Sea) Capture Production (1970-2005) (FAO, 2008). fish, as is reported in the Atlantic Ocean (Clarke et al., Total fisheries production values were converted to rates by 1993), it was assumed that 90% of the diet is cephalopods dividing by the respective surface area. Surface area for the and 10% is fish. For pilot whales and Risso’s dolphins, Mediterranean and Black Sea is 2,966,000km2 (Aubouin and based on a small sample in the Mediterranean Sea (Astruc, Durand-Delga, 2002). Surface area for the Sardinia region 2005; Orsi Relini and Garibaldi, 1992) and the earlier was estimated with ArcView 9.2 as 288,750km2. reviews, diets of 95% cephalopods and 5% fish were assumed. The food of striped dolphins in the Ligurian Sea is comprised of 49.3% fish, 49.7% cephalopods and 1% RESULTS crustaceans (Würtz and Marrale, 1993). Density, biomass and prey consumption The daily prey consumption rate for each species in each During these surveys, 371 sightings (or acoustic detections in six-month season (in kg km-2 d-1) was then estimated by the case of sperm whales) were recorded (Table 1). Five multiplying seasonal density by daily ration. Seasonal cetacean species were recorded on-effort. Striped dolphins consumption was calculated by multiplying daily rates by were the most frequently observed (n=243 sightings), followed the number of days in each six-month period (182.5), and by fin whales (85), sperm whales (27), Risso’s dolphins (10) the annual consumption rate per species (Q, in kg km-2 y-1) and finally pilot whales (6), the only species that was was then the sum of the winter and summer values, with the encountered in summer only. Total survey effort was 2,235km 031-040031-040 JNL JNLvariance 374:Layout 374:Layout calculated 11 as29/12/0929/12/09 the sum of 14:1114:11 the seasonal PagePage 34 variances.34 during October-March and 3,967km during April-September.

Primary production required Striped dolphin The role of cetaceans within the food web of their ecosystem An esw of 489m (CV=8.4%) was estimated for striped was also examined by estimating the proportion of net primary dolphins using a hazard-rate model without adjustment, production required to sustain the prey that they consumed. after truncation at 1,400m. Mean school size was 19.9

3434 031-040 JNLLARAN 374:LayoutLARAN etet al al .:.:1 SEASONALSEASONAL 29/12/09 ESTIMATES ESTIMATES14:11 Page OF OFOF 34 CETACEANS CETACEANSCETACEANS IN ININ THE THETHE LIGURUIAN LIGURUIANLIGURIAN SEA SEA thethe Innes Innes (1987)(1987) model model were were also also plausible. plausible. Similarly, Similarly, Table 1This was estimated using a constant transfer efficiency of 10% 031-040 JNL 374:Layoutetet al. al. 1 29/12/09 14:11 Page 34 031-040 JNLthethe 374:Layout Kenney KenneySurvey eteffortet al. al.1 and (1997)29/12/09(1997) on-effort model modeltotal 14:11 sightings has has been beenPageafter truncation used used34 for for (and the the number ofbetween individuals) successive collected between trophic February levels, 2001TL (Pauly(Pauly and February and and Christensen, Christensen, 2004. principal analyses reported in this paper. 1995). The primary production required (PPR , gC m22 y-1-1)) to to 031-040 JNLSeasonal 374:Layout period 1 No.29/12/09 of surveys 14:11Effort (km)Page 34Fin whale Sperm* whale Pilot whale Risso’s dolphin Striped dolphPPRppin, Total Consumption rates were estimated using Eqns (4) and and (5), supportsupport consumption consumption of of any any prey prey type type p was calculated from andApril partitioned-September into three19 prey categories:3,967 fish; cephalopod;77 (126) 19 (29)consumption6 (171) of that prey4 (39) ( ) using a169 factor (3,520) 10kk, with275being and partitioned into three prey categories: fish; cephalopod; consumption of that prey (Qpp) using a factor 10 , with kk being andOctober zooplankton-March (crustaceans).12 In the2,235 absence of knowledge8 (9) 8 (24)the number0 of trophic steps6 (68) between phytoplankton74 (959) (96 = 1) and zooplankton (crustaceans).34 In the absenceLARAN ofet knowledge al.: SEASONALthe ESTIMATES number of OF trophic CETACEANS steps between IN THE phytoplankton LIGURUIAN ( SEATL = 1) onTotal variation of the ingestion31 rate, the6,202 CVs were85 propagated (135) 27 (53)andand the the given given6 (171) prey prey category: category:10 (107) 243 (4,478) 371 from*Both visual biomass sightingsthe densities and Innes acoustic estimatesdetections(1987) are model throughincluded were for sperm to also the whales plausible.. Similarly, This was estimated using a constant transfer efficiency of 10% 34from biomass densitiesLARANet al.etestimates al.: SEASONAL through ESTIMATES to the OF CETACEANS IN THE LIGURUIAN SEA consumption34consumption estimates, estimates,theLARAN Kenney whilst whilstetet alaware aware al..: SEASONAL(1997) that that the the model ESTIMATES CV CV has value value been OF used CETACEANS for the IN THEbetween LIGURUIAN successive SEA trophic levels, TL (Pauly and Christensen, the Innes (1987)principal model analyses were also reported plausible. in this Similarly, paper. This was estimated1995). using Thea constant primary transfer production efficiency required of 10% ( gC m2 y-1) to would beet underestimated al. LARAN by an.: SEASONAL unknown and ESTIMATES maybe OF CETACEANS IN THE LIGURUIAN SEA PPRp, 34the Innes (1987) model wereet al also plausible. Similarly, This1 was estimated using a constant transfer efficiency of 10%(8)(8) importanttheimportant Kenneyet amount. amount. al. ForConsumption For(1997) the the model group group rates ofhas of species, species,were been estimated used the the sumfor sum using the of of Eqnsbetween (4)http://www.fao.org/fishery/statistics/programme/3,1,2/en and (5), successivesupport trophic consumption levels, (Pauly of any and prey Christensen, type was calculated from the Kenney et al. (1997) model has been used for the between successive trophic levels, TL (Pauly and Christensen,p thevariancesprincipal Innes analyseset of al. theet(1987) al. differentand reported partitioned model components in were this into paper. also three were plausible. prey estimated. categories: Similarly, The fish; cephalopod;Thiswhere1995). was The estimatedisis primary the the energy energyconsumption using production density density a constant required ofrequired of of thatTL the the transfer preyprey. prey. ((PPRPPR (efficiencyQ ,,) isgCisgC using the the m2-2 oftrophic trophic a yy-1 factor 10%-1) to 10k, with k being principal analyses reported in this paper. 1995).E Thepp primary production required ( TLpp gC m2 y-1) to theestimatedestimatedConsumption Kenney percentages percentages ratesand(1997)were zooplankton of of each each estimated model species’ species’ (crustaceans). has using dietdiet been Eqns comprising comprising used (4) In the and for absence (5), the the ofbetweenlevelsupportlevel knowledge of of consumption successive the the prey preythe trophic category category of number any levels, prey of and and trophic type assumed assumed(Pauly stepswasPPR and calculatedp to to between, Christensen, be be 2.2 2.2 phytoplankton from for for ( = 1) Consumptionet al.rates were estimated using Eqns (4) and (5), support consumption of any prey typeTL p was calculated from TL principalthreeandthree partitioned categories categories analyses into were wereon reported three variation based based prey in upon upon this of categories: the previous previous paper. ingestion fish; reviews reviews rate, cephalopod; (Kenney (Kenney the CVs were1995).crustaceans,consumptioncrustaceans, propagated The primary 3.2 3.2of that for forand production cephalopods,prey cephalopods, the ( givenQ ) using required prey and and a category: factor 3.0 3.0p (PPR for for 10 fish fish,k,gC with (Pauly (Pauly m2kybeing-1 and) and to and partitioned into three prey categories: fish; cephalopod; consumption of that prey ( p) using a factor 10p k, with being andConsumption zooplankton,, 1985; 1985; Kenney Kenney rates (crustaceans).from were biomass estimated,, 1997; 1997; In the densities Pauly Paulyusing absence Eqns of estimates (4) knowledge,, 1998) 1998) and (5), as as throughsupportChristensen,the number to consumption the of 1995). trophic The of steps any termsQp between prey in type the phytoplankton denominatorwas calculated (converts k from= 1) etandet al. al. zooplankton (crustaceans).etet al. al. In the absenceetet ofal. al. knowledge the number of trophic steps between phytoplanktonp (TL = 1) andmodifiedon variation partitioned by literatureof theintoconsumption ingestion three and prey data rate, specificcategories: estimates, the CVs to the fish; werewhilst Mediterranean cephalopod; propagated aware that theconsumptionfromandfrom CV the energy energy value given of to toprey that carbon carbon category: prey units units ( ) (Platt, (Platt,using a 1969) 1969) factor and and 10k, from from withTL km kmbeing22 toto on variation of the ingestion rate, the CVs were propagated and the given prey category:Qp k andSea.from zooplankton The biomass food of (crustaceans).would fin densities whales be in underestimatedestimates In summer the absence was through assumed of by knowledge an to tounknown the be andthem22.. number The The maybe primary primary of trophic production production steps between required required phytoplankton was was then then compared compared ( =1) to to from biomass densities estimates through to the TL (8) on100%consumption variation crustaceans, of estimates, theimportant ingestion as the whilst amount. rate, euphausiid aware the ForCVs that the were the group propagated CV of value species,andtotal thetotal the sum net net given primary primary of prey production production category: as as reported reported in in the the literature. literature. consumption estimates, whilst aware thatMeganyctiphanes the CV value fromwould biomass beisis underestimated considered consideredvariances densities as asof its its by estimates the only only an different foodunknown food through resource resource components and (Astruc, (Astruc,to maybe the were estimated. The where is the energy density of the prey. is the trophic norvegicawould be underestimated by an unknown and maybe Ep (8) TL consumption2005;important Orsi amount. Relini estimates,estimated and For Giordano, the whilst percentages group 1992).aware of species, Since that of each the fin the species’whales CV sum value are ofdiet comprising the level of the prey category and assumed(8) to be 2.2 for important amount. For the group of species, the sum of Comparison with fisheries wouldpresentvariances be in of the underestimated the Mediterranean differentthree categories components by Sea an were in unknownwere basedwinter estimated. upon and and previous there maybe The is reviewsAnnualwhere (Kenney globalis the capture energycrustaceans, densityproduction 3.2 of thefor estimates cephalopods,prey. wereis the extracted and trophic 3.0 for fish (Pauly and variances of the different components were estimated. The where Ep is the energy density of the prey. TL is the trophic(8) importantevidenceestimatedevidence of of percentages amount. winter winter feeding, feeding, For of, the 1985; each groupat at species’least leastKenney of close close species, diet to to comprising Sicily Sicily, 1997; the (Canese (Canese sum Pauly the of withlevel, 1998) ofEp asthe preyChristensen,11 categoryandand the the andtime time 1995). assumed series series The ofterms ofTL to the the be in Food Food the 2.2 denominator and and for converts estimated percentageset al. of each species’ dietet al. comprising the et al.levelFishStat of the prey Plus category and assumed to be 2.2 for variancesthree categories,, 2006), 2006), of the no no were differentmodified scaling scaling based componentsby factor factor upon literature previous was was were appliedand applied reviews data estimated. to tospecific (Kenney increase increase The to the MediterraneanwhereAgriculturecrustaceans,is the 3.2Organisation energy forfrom cephalopods, densityenergy of theto of and carbonthe United prey.3.0 forunits Nations fishis (Platt, the(Pauly trophic(FAO), 1969) and and from km2 to etthreeet al. al. categories were based upon previous reviews (Kenney crustaceans,Ep 3.2 for cephalopods, and 3.0 forTL fish (Pauly and estimatedsummersummer, 1985; feeding feeding percentages Kenney rate rateSea. to toThe of account account each food, 1997; species’ for for of winterfin winter Pauly whales diet fasting. fasting. comprising in, summer Based 1998)Based the onon as was assumedlevelavailableChristensen,available of to befrom thefrom 1995). prey the them area. area.2 category The. The Results Results terms primary and in were were the productionassumed averaged averaged denominator to required from from be converts 2.22000 2000 was for to to then compared to et al., 1985; Kenney et al., 1997; Pauly et al., 1998) as Christensen, 1995). The terms in the denominator converts threeinformationmodifiedetinformation al. categories by literature for for were other other100% based andet areas areas crustaceans, al. data upon (Lockyer, (Lockyer, specific previous asto 2007; 2007; the thereviewset Mediterraneanal. Sigurjónsson Sigurjónsson euphausiid (Kenney crustaceans,2005from forenergy two 3.2 todifferent carbon fortotal cephalopods, areas: net units primary (1) (Platt, the and production 1969)total 3.0 Mediterraneanfor and fish as from (Pauly reported km2 andSea to in the literature. modified by literature and data specific to the MediterraneanMeganyctiphanesfrom energy to carbon units (Platt, 1969) and from km2 to andSea.and Víkingsson, Víkingsson,The, 1985; food Kenney of 1997;fin 1997; whales Viale, Viale,,is in 1997; considered1985), 1985),summer Pauly it it was was was as assumed its assumed assumed, only 1998) foodto that thatbe as resourceChristensen,plusm2. (Astruc, The Black primary Sea 1995). global production The dataset terms terms required of in in Capture the the wasdenominator denominator Production then compared converts convert (1950- to etSea. al. The food ofnorvegica fin whaleset al. in summer waset assumed al. to be m2. The primary production required was then compared to modifiedduring100% winter, crustaceans, by literature fin2005; whales as and Orsi the feed data Relini euphausiid mainly specific and on to Giordano, euphausiids the Mediterranean 1992). (90%) Since finfrom2006);total whales net energy (2) areprimary total to carbonfishery production unitsproduction as (Platt, reported (1950-2006) 1969) in and the literature. from considering km2 to 100% crustaceans, as the euphausiid Meganyctiphanes total net primary productionComparison aswith reported fisheries in the literature. Sea.but occasionally The foodis considered of onpresent fin fish whales aswhen in its in the onlyavailable summer Mediterranean food was (10%). resourceMeganyctiphanes assumed SeaFor (Astruc, sperm in to winterbe andmcommercial,commercial,2.there The primary is industrial, industrial, productionAnnual recreational recreational global required capture captures captures was production then and and compared aquaculture aquaculture estimates to were extracted norvegica is considered as its only food resource (Astruc, 100%whales,2005;norvegica Orsi crustaceans, there Relini haveevidence and been been as Giordano, the reports of euphausiid winter 1992). on feeding,two Since stomach fin at leastwhales contents close are to Sicilytotalandand (Canese otherother net primary kinds kinds of ofproductionwith fish fish farming farming as reported (FAO, (FAO,1 and in 2008); 2008); the the literature. time and and (3) (3) series the the of the Food and 2005; Orsi Relini and Giordano, 1992). SinceMeganyctiphanes fin whales are Comparison with fisheriesFishStat Plus frompresentfrom the the in Mediterranean Mediterraneanis the considered Mediterranean, Sea Sea as 2006), its (Astruc, (Astruc, onlySea no in foodscaling 2005; 2005; winter resource Roberts, Roberts, factor and (Astruc, there was 2003); 2003); applied is SardiniaAnnualComparison to increase global region with capture aloneAgriculture fisheries (Tyrrhenian production Organisation Sea estimates to east of were Sardinia the extracted United and Nations (FAO), norvegicapresent in the Mediterraneanet al. Sea in winter and there is Annual global capture production estimates were extracted 2005;bothevidence Orsiincluded of Relini winter onlysummer and feeding, Giordano, cephalopods, feeding at least 1992). rate close mainly to Since account to Sicily fin whales for (Canese winter are fasting.ComparisonCorsica;with BasedFishStatFig. on with1) Plus extractedavailable fisheries1 and the from from time GFCM the series area. (Mediterranean Results of the were Food averaged and and from 2000 to evidence of winter feeding, at least close to SicilyHistioteuthis (Canese with 1 and the time series of the Food and present, 2006), in.. However, However, the no Mediterraneaninformation scaling to to account account factor forSea for for wasother possible possible in winter applied areas consumption consumption (Lockyer,and to increasethere of2007; ofis SigurjónssonAnnualBlackAgricultureFishStat Sea) global Capture Organisation Pluscapture2005 Production productionfor twoof the different (1970-2005) estimates United areas: Nations were (FAO, (1) the extracted (FAO), 2008). total Mediterranean Sea bonnelliiet al., 2006), no scaling factor was applied to increase Agriculture Organisation of the United Nations (FAO), evidencefish,summeretfish, al. as as feedingis is of reported reported winter rateand feeding, into in Víkingsson, account the the Atlantic Atlantic at least for 1997;winter close Ocean Ocean Viale, tofasting. (ClarkeSicily (Clarke 1985), Based (Canese it on, was, assumedwithTotalavailable fisheries that from productiontheplus area.1 and Black Results thevalues Sea time were wereglobal series averaged converted dataset of the from of to Food Capture rates 2000 and by to Production (1950- summer feeding rate to account for winter fasting. Basedetet al. al. on availableFishStat from Plus the area. Results were averaged from 2000 to 1993),information, it 2006), was for assumed no otherduring scaling areas that winter, factor 90% (Lockyer, fin of was whales the applied 2007; diet feed is Sigurjónsson cephalopodsmainlyto increase on euphausiidsAgriculturedividing2005 (90%)for bytwo the Organisation different respective2006); areas: (2) surface of total (1) the the fishery area. United total Surface Mediterranean production Nations area (FAO),(1950-2006) for Sea the considering etinformation al. for other areas (Lockyer, 2007; Sigurjónsson 2005 for two different areas: (1) the total Mediterranean Sea summerandand Víkingsson,10% 10% feeding is is fish. fish. rate 1997;but For For to occasionally pilotaccount pilot Viale, whales whales 1985), for on winter and and fish it was Risso’s Risso’sfasting. when assumed available Baseddolphins, dolphins, that on (10%).availableMediterraneanplus For Black sperm from Sea theand globalcommercial, area. Black dataset Results Sea is of industrial, 2,966,000kmwere Capture averaged recreational Production22 (Aubouin(Aubouin from 2000 captures(1950- and and to and aquaculture and Víkingsson, 1997; Viale, 1985), it was assumed that plus Black Sea global dataset of Capture Production (1950- informationbasedduring on winter, a small for fin other samplewhales, whales areas infeed there the (Lockyer, mainly Mediterraneanhave beenon 2007; euphausiids reports Sigurjónsson Sea on(Astruc, (90%) two stomach2005Durand-Delga,2006); contents for (2) two total different 2002). fisheryand otherareas: Surface production kinds (1) area the of (1950-2006) total for fish the Mediterranean farming Sardinia considering (FAO, region Sea 2008); and (3) the during winter, fin whales feed mainly on euphausiids (90%) 2006); (2) total fishery production (1950-2006) considering and2005;but occasionally Víkingsson, Orsi Relinion 1997;from and fish the Viale, Garibaldi,when Mediterranean 1985), available 1992) it was (10%). Sea and assumed (Astruc, the For earlier sperm 2005; that Roberts,pluswascommercial, estimated Black 2003); Sea industrial, with globalSardinia dataset recreational region ofasas Capture alone 288,750kmcaptures 288,750km (Tyrrhenian Production and22.. aquaculture Sea (1950- to east of Sardinia and but occasionally on fish when available (10%). For sperm commercial, industrial,ArcView recreational 9.2 captures and aquaculture duringreviews,whales,reviews, winter, there diets diets havefin of ofboth whales 95% 95% been includedfeed cephalopodsreports cephalopods mainly on only two on and and cephalopods,euphausiids stomach 5% 5% fish fish contents (90%) were were mainly 2006);and other (2) kindstotal fishery ofCorsica; fish production farming Fig. 1) (FAO, extracted (1950-2006) 2008); from consideringand GFCM (3) the (Mediterranean and whales, there have been reports on two stomach contents Histioteuthisand other kinds of fish farming (FAO, 2008); and (3) the butassumed.fromassumed. occasionally the Mediterranean The The food food on of of fish striped striped Sea when. However, (Astruc, dolphins dolphins available 2005; to in in accountthe the(10%). Roberts, Ligurian Ligurian Forfor possible 2003); sperm Sea Sea is is consumptioncommercial,Sardinia region of industrial, aloneBlack (Tyrrhenian recreational Sea) Capture Sea captures to Production east and of Sardinia aquaculture (1970-2005) and (FAO, 2008). from the Mediterraneanbonnellii Sea (Astruc, 2005; Roberts, 2003); Sardinia region alone (Tyrrhenian Sea to east of Sardinia and whales,comprisedbothcomprised included there of of have 49.3% 49.3% onlyfish, been cephalopods,as fish, fish, reports is reported49.7% 49.7% on cephalopodstwo cephalopods mainly in thestomach Atlantic andcontents and Ocean 1% 1% (ClarkeandRESULTSCorsica; other Fig. kinds, 1) extractedof Total fish fisheries farming from GFCM production (FAO, (Mediterranean 2008); values and were (3) and convertedthe to rates by both included only cephalopods, mainly Histioteuthis Corsica;et al. Fig. 1) extracted from GFCM (Mediterranean and fromcrustaceanscrustaceans the. Mediterranean However, (Würtz (Würtz1993), and and to account Marrale,Marrale,Sea it was (Astruc, for assumed 1993). 1993). possible 2005; that Roberts,consumption 90%Histioteuthis of 2003); the of diet is cephalopodsSardiniaBlack Sea) region Capture alonedividing Production (Tyrrhenian by the (1970-2005) Searespective to east surface of (FAO, Sardinia area. 2008). and Surface area for the bonnellii. However, to account for possible consumption of Density,Black Sea) biomass Capture and Production prey consumption (1970-2005) (FAO, 2008). bothfish,bonnelliiThe as included daily is reported prey onlyand consumption in 10% cephalopods, the Atlanticis fish. rate for For Ocean mainly each pilot species (Clarke whales in andeach , Risso’sCorsica;DuringTotal dolphins, fisheries these Fig. surveys, 1) production extractedMediterranean 371 sightingsvalues from GFCM and were (or Black convertedacoustic (Mediterranean Sea is detections to2,966,000km rates and by in 2 (Aubouin and fish, as is reported in the Atlantic Ocean (ClarkeHistioteuthiset al., Total fisheries production values were converted to rates by six-month1993),six-month it. was However, season season assumedbased (in (in to kg kg account that on km km a 90%-2 small-2 ford-1-1 of)) possible sample thewas was diet then then in consumption is the estimated estimated cephalopods Mediterraneanet al. bybyof SeaBlackthedividingthe (Astruc, case case Sea) by of of Capturethe sperm sperm respectiveDurand-Delga, whales) whales) Production surface were were (1970-2005) 2002).area. recorded recorded Surface Surface (Table (Table (FAO, area area 1). 1). for2008). for Five Five the the Sardinia region bonnellii1993), it was assumed that 90% of the diet is cephalopods dividing by the respective surface area. Surface area for the fish,multiplyingand 10% as is is reported seasonalfish.2005; For in density pilot the Orsi Atlantic whales Relini by daily Oceanand and Risso’s ration.Garibaldi, (Clarke dolphins, Seasonal 1992), andTotalcetaceanMediterraneancetacean the earlier fisheries species species productionand werewas were Black estimated recorded recorded Sea values is 2,966,000km with on-effort.were on-effort. converted Striped Striped2 (Aubouin toas dolphins dolphinsrates 288,750km and by 2. and 10% is fish. For pilot whales and Risso’s dolphins,et al. Mediterranean and Black Sea is 2,966,000kmArcView2 (Aubouin 9.2 and 1993),consumptionbasedconsumption on it was a small was wasassumed samplereviews, calculated calculated that in diets 90%the by by Mediterranean multiplying multiplyingof of the 95% diet cephalopods is daily daily cephalopodsSea rates(Astruc, ratesby andby 5%dividingwereDurand-Delga, fish the were mostby the frequently 2002).respective Surface observed surface area ( area.=243 for Surface the sightings), Sardinia area followed for region the based on a small sample in the Mediterranean Sea (Astruc, Durand-Delga, 2002). Surface arean for the Sardinia region andthe2005;the number number 10% Orsi is of ofRelini fish. days daysassumed. For and in inpilot each each Garibaldi, The six-monthwhales six-month food 1992) of and striped period period Risso’s and dolphins (182.5), (182.5), the dolphins, earlier andin and the LigurianMediterraneanbywas fin estimated Sea whales is (85), with and Black spermArcView Sea whales 9.2 is 2,966,000kmas (27), 288,750km Risso’s2 (Aubouin2 dolphins. (10) and 2005; Orsi Relini and Garibaldi, 1992) and the earlier was estimated withRESULTS as 288,750km2. basedthereviews,the annual annual on a diets consumption consumptionsmall of samplecomprised 95% rate rate in cephalopods the per per of Mediterranean species species49.3% and (Q, (Q,fish, in5% in 49.7%Sea kg kg fish km km (Astruc,-2-2 werecephalopodsy-1-1)) Durand-Delga,andand and finally finally 1% pilot pilot 2002). whales whalesArcView Surface (6), (6), 9.2 area the the foronly only the species species Sardinia that that region was was reviews, diets of 95% cephalopods and 5% fish were 2005;wasassumed. then Orsi the The Relini sum foodcrustaceans of of and the striped winter Garibaldi, dolphins (Würtz and summer 1992) and in the Marrale, andvalues, Ligurian the 1993). with earlier Sea the is wasencounteredencountered estimated in in with summer summerDensity,ArcView only. only. biomass Total9.2 Totalas survey survey 288,750km and preyeffort effort consumption2 was was. 2,235km 2,235km assumed. The food of striped dolphins in the Ligurian Sea is RESULTS reviews,variancecomprised calculated diets of 49.3% of 95%as The the fish, daily cephalopods sum 49.7% prey of the consumption cephalopods seasonal and 5% variances. rate fish and for were 1% each speciesduring in October-March each During and these 3,967km surveys, during 371 April-September. sightings (or acoustic detections in comprised of 49.3% fish, 49.7% cephalopods and 1% RESULTS assumed.crustaceans The (Würtz foodsix-month of and striped Marrale, season dolphins 1993). (in in kg the km Ligurian-2 d-1) Sea was is then estimatedDensity, biomassby the and case prey of consumption sperm whales) were recorded (Table 1). Five comprisedcrustaceansThe daily of (Würtz prey 49.3%multiplying consumption and fish, Marrale, 49.7% seasonal rate 1993). for cephalopods each density species by and in daily each 1% ration.RESULTSDuringDensity, Seasonal these biomass surveys,cetacean and 371 prey sightings species consumption were(or acoustic recorded detections on-effort. in Striped dolphins PrimaryThe daily production prey consumption required rate for each species in each StripedDuring these dolphin surveys, 371 sightings (or acoustic detections in crustaceansThesix-month role of season cetaceans (Würtzconsumption (in and within kg Marrale, km the-2 wasd food-1 1993).) calculatedwas web then of their estimated by ecosystem multiplying by dailyAnthe rates case by of 489mspermwere (CV=8.4%) whales) the most were frequently was recorded estimated observed (Table for ( 1). striped=243 Five sightings), followed six-month season (in kg km-2 d-1) was then estimated by Density,the caseeswesw biomass of sperm and whales) prey consumption were recorded (Table 1).n Five wasmultiplyingThe also daily examined prey seasonalthe consumption byestimating number density of rate theby days proportion for daily in each each ration. species of six-month net Seasonal primary in each period (182.5),Duringdolphinscetacean these and species using surveys, a wereby hazard-rate fin 371 recorded whales sightings model(85), on-effort. (or sperm acoustic without Striped whales detections adjustment, (27),dolphins Risso’s in dolphins (10) multiplying seasonal density by daily ration. Seasonal cetacean species were recorded on-effort. Striped dolphins six-monthproductionconsumption season required wasthe calculated(in to annual kg sustain km consumption-2 by thed-1 multiplying prey) was that then rate they daily estimated per consumed. species rates by (Q, in kgtheafterwereafter km case the-2 truncation truncationy most-1 of) sperm frequently at atand whales) 1,400m. 1,400m. finally observed were Mean Mean pilot (n recorded=243 whales school school sightings), (Table (6),size size the was was followed 1). only 19.9Five 19.9 species that was multiplyingtheconsumption number of seasonal was dayswas calculated in then density each the six-month by sum by multiplying of daily the period winter ration. daily (182.5), and Seasonal rates summer and by values,cetaceanbywere fin with the whales themost species frequently(85), wereencountered sperm recorded observed whales in summer on-effort. ((27),n=243 Risso’s sightings),only. Striped Total dolphins followeddolphins survey (10) effort was 2,235km consumptionthe annual number consumption of was daysvariance calculated in each rate calculated per six-month by speciesmultiplying as periodthe (Q, sum in daily kg(182.5), of km ratesthe-2 seasonaly and by-1) variances.wereandby fin finallythe whales most pilot frequently (85),during whales sperm observed October-March whales (6), the ( (27),=243 only Risso’s and sightings), species 3,967km dolphins that followed during (10)was April-September. the annual consumption rate per species (Q, in kg km-2 y-1) and finally pilot whales (6), then only species that was thewas number then the of sum days ofthe in each winter six-month and summer period values, (182.5), with and theTableTable 11byencountered fin whales in (85), summer sperm only. whales Total (27), survey Risso’s effort dolphinswas 2,235km (10) 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 34 thevariancewas annual then calculated the consumption sum of as the thewinter rate sum per ofand species the summer seasonal (Q, values, in variances. kg km with-2 y the-1) andduringencountered finally October-March in pilot summer whales and only. 3,967km (6), Total the survey during only effort April-September. species was that 2,235km was varianceSurveySurvey calculated efforteffort Primary andand as onon the--efforteffort sum production totaltotal of sightingssightings the seasonal required afterafter ttruncationruncation variances. (and(and numbernumber ofof during individuals)individuals) October-March collectedcollectedStriped betweenbetween and FebruaryFebruary dolphin3,967km 20012001 during andand FebruaryFebruary April-September. 20042004.. was then the sumThe of the role winter of cetaceans and summer within values, the food with web the of theirencountered ecosystem in summerAn esw only.of Total 489m survey (CV=8.4%) effort was was 2,235km estimated for striped Seasonal period No. of surveys Effort (km) Fin whale Sperm* whale Pilot whale Risso’s dolphin Striped dolphin Total variancePrimarySeasonal calculatedperiod productionwas asNo. requiredalso theof surveys sumexamined of theEffort by seasonal estimating(km) variances.Fin thewhale proportionSperm* ofwhaleduringStriped net primary October-MarchPilot dolphinwhale dolphinsRisso’s anddolphin 3,967km usingStriped a during hazard-ratedolph April-September.in modelTotal without adjustment, ThePrimaryApril role-September of production cetaceansproduction within required19 the required food3,967 web to sustain of their77 the ecosystem(126) prey that19 they (29)AnStriped consumed. dolphin6of(171) 489mafter (CV=8.4%)4 truncation (39) was at169 estimated 1,400m.(3,520) Mean for275 striped school size was 19.9 TheApril role-September of cetaceans within19 the food3,967 web of their77 ecosystem(126) 19 (29)An esw 6of(171) 489m (CV=8.4%)4 (39) was169 estimated (3,520) for275 striped PrimarywasOctober also--March examined production by estimating required1212 the proportion2,2352,235 of net88 (9) (9) primary 88 (24) (24)Stripeddolphinsesw dolphin using00 a hazard-rate66 (68) (68) model7474 (959) without(959) adjustment,9696 TheproductionwasTotalTotal rolealso examinedof requiredcetaceans by to withinestimating sustain3131 the the foodthe prey proportion6,2026,202 web that of they their of8585 net consumed. ecosystem (135)(135) primary 2727 (53)(53)Anafterdolphins truncation66of using(171)(171) 489m a at hazard-rate (CV=8.4%) 1,400m.1010 (107)(107) Mean model was243243 school estimated (4,478)(4,478) without size adjustment, for was371371 striped 19.9 production required to sustain the prey that they consumed. afteresw truncation at 1,400m. Mean school size was 19.9 was*B*Bothoth also visualvisual examined sightingssightings by andand estimating acousticacoustic detectionsdetections the proportion aarereincludedincluded of net forfor spermsperm primary whaleswhales.. dolphins usingTable a1 hazard-rate model without adjustment, 34 LARAN et al.: SEASONAL ESTIMATES OF CETACEANS IN THE LIGURUIAN SEA production required to sustainSurvey theeffort prey and on that-effort they total consumed. sightings after truncationafter (and truncation number of at individuals) 1,400m. collected Mean between school February sizewas 2001 and 19.9 February 2004. the Innes et al. (1987) model were also plausible. Similarly, This was estimated using a constant transfer efficiency of 10% Table 1 Seasonal period No. of surveys Effort (km)Table Fin11 whale Sperm* whale Pilot whale Risso’s dolphin Striped dolphin Total the Kenney et al. (1997) model has been used for the betweenSurvey successive effort and trophic on-effort levels, total sightingsTL (Pauly after and truncation Christensen, (and number of 1individuals)http://www.fao.org/fishery/statistics/programme/3,1,2/enhttp://www.fao.org/fishery/statistics/programme/3,1,2/en collected between February 2001 and February 2004. principal analyses reported in this paper. 1995). TheSurvey primary effort andApril production on--Septembereffort total required sightings ( after19 truncationgC m2 (andy3,967-1) number to Table of 177 individuals) (126) collected19 (29) between February6 (171) 2001 and4 February (39) 2004.169 (3,520) 275 Seasonal period No. of surveys Effort (km)PPRp, Fin whale Sperm* whale Pilot whale Risso’s dolphin Striped dolphin Total Consumption rates were estimated using Eqns (4) and (5), supportSeasonalSurvey consumption period effort andOctoberNo. ofon of- anyeffortsurveys-March prey total sightings typeEffortp(km)was after12 calculatedtruncationFin whale (and2,235 from numberSperm* ofwhale individuals)8 (9) Pilot collectedwhale8 (24) betweenRisso’s dolphinFebruary0 2001Striped anddolph6 February (68)in 2004Total. 74 (959) 96 and partitioned into three prey categories: fish; cephalopod; consumptionApril-September of thatTotal prey19 ( ) using a3,967 factor31 10k,77 with (126)6,202being 19 (29)85 (135) 6 (171)27 (53) 4 (39)6 (171) 169 (3,520)10 (107) 275243 (4,478) 371 SeasonalApril-September period No. of19surveysQp Effort3,967(km) Fin77 whale(126)k Sperm*19 (29)whale Pilot6 (171)whale Risso’s4 (39)dolphin Striped169 (3,520)dolphin Total275 and zooplankton (crustaceans). In the absence of knowledge theOctober number-March of trophic*Both steps 12visual between sightings2,235 phytoplankton and acoustic detections8 (9) (TL = are 1)included8 (24) for sperm whales0 . 6 (68) 74 (959) 96 TotalOctober-March 3112 6,2022,235 858 (135) (9) 278 (24)(53) 6 (171)0 106 (107) (68) 24374 (4,478)(959) 37196 on variation of the ingestion rate, the CVs were propagated andAprilTotal the-September given prey category:1931 3,9676,202 7785 (126)(135) 1927 (29)(53) 66 (171)(171) 104 (39)(107) 169243 (3,520)(4,478) 275371 October*Both visual-March sightings and acoustic12 detections2,235 are included for8 (9) sperm whales8. (24) 0 6 (68) 74 (959) 96 from biomass densities estimates through to the *Both visual sightings and acoustic detections are included for sperm whales. consumption estimates, whilst aware that the CV value Total 31 6,202 85 (135) 27 (53) 6 (171) 1http://www.fao.org/fishery/statistics/programme/3,1,2/en10 (107) 243 (4,478) 371 would be underestimated by an unknown and maybe *Both visual sightings and acoustic detections are included for sperm whales. (8) 1http://www.fao.org/fishery/statistics/programme/3,1,2/en important amount. For the group of species, the sum of 1http://www.fao.org/fishery/statistics/programme/3,1,2/en variances of the different components were estimated. The where Ep is the energy density of the prey. TL is the trophic estimated percentages of each species’ diet comprising the level of the prey category and assumed to be 2.2 for 1http://www.fao.org/fishery/statistics/programme/3,1,2/en three categories were based upon previous reviews (Kenney crustaceans, 3.2 for cephalopods, and 3.0 for fish (Pauly and et al., 1985; Kenney et al., 1997; Pauly et al., 1998) as Christensen, 1995). The terms in the denominator converts modified by literature and data specific to the Mediterranean from energy to carbon units (Platt, 1969) and from km2 to Sea. The food of fin whales in summer was assumed to be m2. The primary production required was then compared to 100% crustaceans, as the euphausiid Meganyctiphanes total net primary production as reported in the literature. norvegica is considered as its only food resource (Astruc, 2005; Orsi Relini and Giordano, 1992). Since fin whales are Comparison with fisheries present in the Mediterranean Sea in winter and there is Annual global capture production estimates were extracted evidence of winter feeding, at least close to Sicily (Canese with FishStat Plus1 and the time series of the Food and et al., 2006), no scaling factor was applied to increase Agriculture Organisation of the United Nations (FAO), summer feeding rate to account for winter fasting. Based on available from the area. Results were averaged from 2000 to information for other areas (Lockyer, 2007; Sigurjónsson 2005 for two different areas: (1) the total Mediterranean Sea and Víkingsson, 1997; Viale, 1985), it was assumed that plus Black Sea global dataset of Capture Production (1950- during winter, fin whales feed mainly on euphausiids (90%) 2006); (2) total fishery production (1950-2006) considering but occasionally on fish when available (10%). For sperm commercial, industrial, recreational captures and aquaculture whales, there have been reports on two stomach contents and other kinds of fish farming (FAO, 2008); and (3) the from the Mediterranean Sea (Astruc, 2005; Roberts, 2003); Sardinia region alone (Tyrrhenian Sea to east of Sardinia and both included only cephalopods, mainly Histioteuthis Corsica; Fig. 1) extracted from GFCM (Mediterranean and bonnellii. However, to account for possible consumption of Black Sea) Capture Production (1970-2005) (FAO, 2008). fish, as is reported in the Atlantic Ocean (Clarke et al., Total fisheries production values were converted to rates by 1993), it was assumed that 90% of the diet is cephalopods dividing by the respective surface area. Surface area for the and 10% is fish. For pilot whales and Risso’s dolphins, Mediterranean and Black Sea is 2,966,000km2 (Aubouin and based on a small sample in the Mediterranean Sea (Astruc, Durand-Delga, 2002). Surface area for the Sardinia region 2005; Orsi Relini and Garibaldi, 1992) and the earlier was estimated with ArcView 9.2 as 288,750km2. reviews, diets of 95% cephalopods and 5% fish were assumed. The food of striped dolphins in the Ligurian Sea is comprised of 49.3% fish, 49.7% cephalopods and 1% RESULTS crustaceans (Würtz and Marrale, 1993). Density, biomass and prey consumption The daily prey consumption rate for each species in each During these surveys, 371 sightings (or acoustic detections in six-month season (in kg km-2 d-1) was then estimated by the case of sperm whales) were recorded (Table 1). Five multiplying seasonal density by daily ration. Seasonal cetacean species were recorded on-effort. Striped dolphins consumption was calculated by multiplying daily rates by were the most frequently observed (n=243 sightings), followed the number of days in each six-month period (182.5), and by fin whales (85), sperm whales (27), Risso’s dolphins (10) the annual consumption rate per species (Q, in kg km-2 y-1) and finally pilot whales (6), the only species that was was then the sum of the winter and summer values, with the encountered in summer only. Total survey effort was 2,235km variance calculated as the sum of the seasonal variances. during October-March and 3,967km during April-September.

Primary production required Striped dolphin The role of cetaceans within the food web of their ecosystem An esw of 489m (CV=8.4%) was estimated for striped was also examined by estimating the proportion of net primary dolphins using a hazard-rate model without adjustment, production required to sustain the prey that they consumed. after truncation at 1,400m. Mean school size was 19.9

Table 1 Survey effort and on-effort total sightings after truncation (and number of individuals) collected between February 2001 and February 2004. Seasonal period No. of surveys Effort (km) Fin whale Sperm* whale Pilot whale Risso’s dolphin Striped dolphin Total April-September 19 3,967 77 (126) 19 (29) 6 (171) 4 (39) 169 (3,520) 275 October-March 12 2,235 8 (9) 8 (24) 0 6 (68) 74 (959) 96 Total 31 6,202 85 (135) 27 (53) 6 (171) 10 (107) 243 (4,478) 371 *Both visual sightings and acoustic detections are included for sperm whales.

1http://www.fao.org/fishery/statistics/programme/3,1,2/en 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 34

34 LARAN et al.: SEASONAL ESTIMATES OF CETACEANS IN THE LIGURUIAN SEA the Innes et al. (1987) model were also plausible. Similarly, This was estimated using a constant transfer efficiency of 10% the Kenney et al. (1997) model has been used for the between successive trophic levels, TL (Pauly and Christensen, 2 -1 principal analyses reported in this paper. 1995). The primary production required (PPRp, gC m y ) to Consumption rates were estimated using Eqns (4) and (5), support consumption of any prey type p was calculated from k and partitioned into three prey categories: fish; cephalopod; consumption of that prey (Qp) using a factor 10 , with k being and zooplankton (crustaceans). In the absence of knowledge the number of trophic steps between phytoplankton (TL = 1) on variation of the ingestion rate, the CVs were propagated and the given prey category: from biomass densities estimates through to the consumption estimates, whilst aware that the CV value would be underestimated by an unknown and maybe (8) important amount. For the group of species, the sum of variances of the different components were estimated. The where Ep is the energy density of the prey. TL is the trophic estimated percentages of each species’ diet comprising the level of the prey category and assumed to be 2.2 for three categories were based upon previous reviews (Kenney crustaceans, 3.2 for cephalopods, and 3.0 for fish (Pauly and et al., 1985; Kenney et al., 1997; Pauly et al., 1998) as Christensen, 1995). The terms in the denominator converts modified by literature and data specific to the Mediterranean from energy to carbon units (Platt, 1969) and from km2 to Sea. The food of fin whales in summer was assumed to be m2. The primary production required was then compared to 100% crustaceans, as the euphausiid Meganyctiphanes total net primary production as reported in the literature. norvegica is considered as its only food resource (Astruc, 2005; Orsi Relini and Giordano, 1992). Since fin whales are Comparison with fisheries present in the Mediterranean Sea in winter and there is Annual global capture production estimates were extracted evidence of winter feeding, at least close to Sicily (Canese with FishStat Plus1 and the time series of the Food and et al., 2006), no scaling factor was applied to increase Agriculture Organisation of the United Nations (FAO), summer feeding rate to account for winter fasting. Based on available from the area. Results were averaged from 2000 to information for other areas (Lockyer, 2007; Sigurjónsson 2005 for two different areas: (1) the total Mediterranean Sea and Víkingsson, 1997; Viale, 1985), it was assumed that plus Black Sea global dataset of Capture Production (1950- during winter, fin whales feed mainly on euphausiids (90%) 2006); (2) total fishery production (1950-2006) considering but occasionally on fish when available (10%). For sperm commercial, industrial, recreational captures and aquaculture whales, there have been reports on two stomach contents and other kinds of fish farming (FAO, 2008); and (3) the from the Mediterranean Sea (Astruc, 2005; Roberts, 2003); Sardinia region alone (Tyrrhenian Sea to east of Sardinia and both included only cephalopods, mainly Histioteuthis Corsica; Fig. 1) extracted from GFCM (Mediterranean and bonnellii. However, to account for possible consumption of Black Sea) Capture Production (1970-2005) (FAO, 2008). fish, as is reported in the Atlantic Ocean (Clarke et al., Total fisheries production values were converted to rates by 1993), it was assumed that 90% of the diet is cephalopods dividing by the respective surface area. Surface area for the and 10% is fish. For pilot whales and Risso’s dolphins, Mediterranean and Black Sea is 2,966,000km2 (Aubouin and based on a small sample in the Mediterranean Sea (Astruc, Durand-Delga, 2002). Surface area for the Sardinia region 2005; Orsi Relini and Garibaldi, 1992) and the earlier was estimated with ArcView 9.2 as 288,750km2. reviews, diets of 95% cephalopods and 5% fish were assumed. The food of striped dolphins in the Ligurian Sea is comprised of 49.3% fish, 49.7% cephalopods and 1% RESULTS crustaceans (Würtz and Marrale, 1993). Density, biomass and prey consumption The daily prey consumption rate for each species in each During these surveys, 371 sightings (or acoustic detections in six-month season (in kg km-2 d-1) was then estimated by the case of sperm whales) were recorded (Table 1). Five multiplying seasonal density by daily ration. Seasonal cetacean species were recorded on-effort. Striped dolphins consumption was calculated by multiplying daily rates by were the most frequently observed (n=243 sightings), followed the number of days in each six-month period (182.5), and by fin whales (85), sperm whales (27), Risso’s dolphins (10) the annual consumption rate per species (Q, in kg km-2 y-1) and finally pilot whales (6), the only species that was was then the sum of the winter and summer values, with the encountered in summer only. Total survey effort was 2,235km 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 35 variance calculated as the sum of the seasonal variances. during October-March and 3,967km during April-September. 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 35

Primary production required Striped dolphin The role of cetaceans within the food web of their ecosystem An esw of 489m (CV=8.4%) was estimated for striped was also examined by estimating the proportion of net primary dolphins using a hazard-rate model without adjustment, production required to sustain the prey that they consumed. after truncation at 1,400m. Mean school size was 19.9 J. CETACEAN RES. MANAGE. 11(1):31–40, 2009 35 J. CETACEANCETACEAN RES. MANAGE. MANAGE. 11(1):31–11(1):31–40,40,­­ 2010 2009 35 Table 2 Table 1 Table 2 Mean body masses (W, in kg) for males, females, and both sexes averaged, for five cetacean species in the Ligurian Sea, and Survey effort and on-effort total sightings after truncation (and number of individuals) collected between February 2001 and February 2004. Mean body masses (W, in kg) for males,-1 females, and both sexes averaged, for five cetacean species in the Ligurian Sea, and mean daily ration per individual (kg d-1, and as % of body mass in parentheses) estimated from four different models: (1) Innes mean daily ration per individual (kg d-1, and as % of body mass in parentheses) estimated from four different models: (1) Innes et al. (1987); (2) Trites et al. (1997); (3) Kenney et al. (1997); (4) Sigurjónsson and Víkingsson (1997). Model 3 (in bold) was Seasonal period No. of surveys Effort (km) Fin whale Sperm* whale Pilot whale Risso’s dolphin Striped dolphin Total et al. (1987); (2) Trites et al. (1997); (3) Kenney et al. (1997); (4) Sigurjónsson and Víkingsson (1997). Model 3 (in bold) was selected for use in the analysis reported in this paper. Mean body masses were taken from Trites and Pauly (1998) or estimated selected for use in the analysis reported in this paper. Mean body masses were taken from Trites and Pauly (1998) or estimated April-September 19 3,967 77 (126) 19 (29) 6 (171) 4 (39) 169 (3,520) 275 using their regression models from maximum lengths (Lmax, in cm) from Mediterranean specimens (F. Dhermain, GECEM and using their regression models from maximum lengths (Lmax, in cm) from Mediterranean specimens (F. Dhermain, GECEM and October-March 12 2,235 8 (9) 8 (24) 0 6 (68) 74 (959) 96 using their regression models from maximum lengths ( max, in cm) from Mediterranean specimens (F. Dhermain, GECEM and O. Van Canneyt, CRMM, pers. comm.). Total 31 6,202 85 (135) 27 (53) 6 (171) 10 (107) 243 (4,478) 371 O. Van Canneyt, CRMM,- pers. University comm.) of. La Rochelle, pers. comm.). Lmax W Daily ration *Both visual sightings and acoustic detections are included for sperm whales. Lmax W Daily ration Species � � � � Mean (1) (2) (3) (4) Species � � � � Mean (1) (2) (3) (4) Fin whale 2,000 2,000 31,429 30,832 31,131 484 (1.6) 393 (1.3) 410 (1.3) 680 (2.2) 1 Fin whale 2,000 2,000 31,429 30,832 31,131 484 (1.6) 393 (1.3) 410 (1.3) 680 (2.2) http://www.fao.org/fishery/statistics/programme/3,1,2/en Sperm whale 1,500 na 16,083 10,098 12,492 233 (1.9) 189 (1.5) 244 (2.0) 393 (3.1) Sperm whale 1,500 na 16,083 10,098 12,492 233 (1.9) 189 (1.5) 244 (2.0) 393 (3.1) Pilot whale 600 500 689 450 546 19.0 (3.5) 15.5 (2.8) 23.6 (4.3) 34.2 (6.3) Pilot whale 600 500 689 450 546 19.0 (3.5) 15.5 (2.8) 23.6 (4.3) 34.2 (6.3) Risso’s dolphin na na 236 211 224 9.3 (4.2) 7.6 (3.4) 12.1 (5.4) 17.0 (7.6) Risso’s dolphin na na 236 211 224 9.3 (4.2) 7.6 (3.4) 12.1 (5.4) 17.0 (7.6) Striped dolphin 227 225 68 65 66 3.5 (5.3) 2.9 (4.3) 4.4 (6.7) 6.0 (9.1) Striped dolphin 227 225 68 65 66 3.5 (5.3) 2.9 (4.3) 4.4 (6.7) 6.0 (9.1)

(CV=9.4%) in April-September and 10.9 (CV=13.5%) in October-March. The maximum density was observed in -2 April-September with 0.87 individuals km-2 (CV=15.2%). The density in winter was somewhat less than half of the summer density at 0.37 (CV=21.7%), with a significant difference (Z-test=3.23, <0.005). difference (Z-test=3.23, p<0.005). Maximum lengths of stranded striped dolphins from the Mediterranean were 227cm for males and 225cm for females (from 406 males and 327 females; F. Dhermain, GECEM and O. Van Van Canneyt, Canneyt, CRMM, CRMM -pers. University comm.). of The La Rochelle,average weights pers. comm.). computed The from average the Trites weights and computed Pauly (1998) from theregressions Trites and were Pauly 68kg (1998) and regressions 65kg, respectively, were 68kg and and 65kg, the respectively,average for and the speciesthe average was for 66kg the (Tablespecies 2).was 66kg (Table 2). -2 The seasonal biomass densities were 57.6kg km-2 -2 (CV=15.2%) in April-September and 24.5kg km-2 (CV=21.7%) in October-March (Fig. 3). The average daily ration for a striped dolphin was estimated from the four -1 different models to range from 2.9 to 6.0kg d-1 (4.3-9.1% of -1 body mass, Table 2), with 4.4kg d-1 estimated from Kenney et al. (1997) model. The striped dolphin annual consumption et al. -2 -1 rate was estimated to be 999kg km-2 y-1 (CV=17.7%): 492kg of fish; 497kg of cephalopods; and 10kg of crustaceans (Table 3).

Risso’s dolphin Risso’s dolphin sightings were truncated at 600m and an Risso’s dolphin sightings were truncated at 600m and an esw of 430m (CV=8.9%) was estimated using a half-normal Fig. 3. Estimated biomass density (in kg km-2) for each species for April- of 430m (CV=8.9%) was estimated using a half-normal Fig. 3. Estimated biomass density (in kg km-2) for each species for April- September (open bars) and October-March (filled bars) periods. Error model. Mean school size was 9.8 (CV=43.2%) in April- September (open bars) and October-March (filled bars) periods. Error model. Mean school size was 9.8 (CV=43.2%) in April- bars represent the standard errors. bars represent the standard errors. Table 3 Table 3 -2 -1 -2 -1 Seasonal (kg km-2 d-1) and annual (kg km-2 y-1) estimates of consumption Seasonal (kg km-2 d-1) and annual (kg km-2 y-1) estimates of consumption of three categories of prey by five species of cetaceans in the Ligurian Sea. September and 11.3 (CV=41.2%) in October-March. These of three categories of prey by five species of cetaceans in the Ligurian Sea. September and 11.3 (CV=41.2%) in October-March. These results lead to an extrapolated winter density of 0.035 Season -2 Season individuals km-2 (CV=58.2%), decreasing to 0.011 Species Prey Apr.-Sep. Mar.-Oct. Annual (CV=58.9%) during summer. Risso’s dolphins were the only Species Prey Apr.-Sep. Mar.-Oct. Annual species with a substantially higher density in winter than in Sperm whale Fish 0.01 0.01 4 species with a substantially higher density in winter than in Sperm whale Fish 0.01 0.01 4 summer, differing by a factor of about three, but with no Cephalopods 0.09 0.12 37 summer, differing by a factor of about three, but with no Cephalopods 0.09 0.12 37 Pilot whale Fish 0.03 0.00 6 significant difference due to large CVs (Z-test=1.10, p>0.30). Pilot whale Fish 0.03 0.00 6 significant difference due to large CVs (Z-test=1.10, p>0.30). Cephalopods 0.60 0.00 110 Maximum lengths of Risso’s dolphin from the French Cephalopods 0.60 0.00 110 Maximum lengths of Risso’s dolphin from the French Risso’s dolphin Fish 0.01 0.02 5 Mediterranean stranding network differed by only 20cm Risso’s dolphin Fish 0.01 0.02 5 Mediterranean stranding network differed by only 20cm Cephalopods 0.13 0.41 98 Cephalopods 0.13 0.41 98 from the global values of 380cm for males and 360cm for Striped dolphin Fish 1.89 0.80 492 from the global values of 380cm for males and 360cm for Striped dolphin Fish 1.89 0.80 492 females reported by Trites and Pauly (1998) and were based Cephalopods 1.91 0.81 497 females reported by Trites and Pauly (1998) and were based Cephalopods 1.91 0.81 497 Crustaceans 0.04 0.02 10 on small sample sizes (n<20 for both males and females). Crustaceans 0.04 0.02 10 on small sample sizes (n<20 for both males and females). All odontocetes Fish 1.94 0.84 507 Therefore average weights were used for males and females All odontocetes Fish 1.94 0.84 507 Therefore average weights were used for males and females Cephalopods 2.73 1.33 742 as in Trites and Pauly (1998); 236kg and 211kg, respectively. Cephalopods 2.73 1.33 742 as in Trites and Pauly (1998); 236kg and 211kg, respectively. Crustaceans 0.04 0.02 10 Crustaceans 0.04 0.02 10 The average for the species was 224kg (Table 2). Fin whale Fish 0.00 0.07 13 The average for the species was 224kg (Table 2). Fin whale Fish 0.00 0.07 13 The seasonal biomass densities were 7.9kg km-2 Crustaceans 5.66 0.65 1,150 The seasonal biomass densities were 7.9kg km-2 Crustaceans 5.66 0.65 1,150 -2 All species Fish 1.94 0.91 521 (CV=58.2%) in October-March and 2.6kg km-2 All species Fish 1.94 0.91 521 (CV=58.2%) in October-March and 2.6kg km Cephalopods 2.73 1.33 742 (CV=58.9%) in April-September (Fig. 3). The average daily Cephalopods 2.73 1.33 742 (CV=58.9%) in April-September (Fig. 3). The average daily Crustaceans 5.69 0.66 1,160 ration for Risso’s dolphin was estimated to range from 7.6 to Crustaceans 5.69 0.66 1,160 ration for Risso’s dolphin was estimated to range from 7.6 to Total 10.4 2.9 2,422 -1 Total 10.4 2.9 2,422 17.0kg d-1 (3.4-7.6% of body mass, Table 2). From the 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 36

36 LARAN et al.:.: SEASONAL ESTIMATESESTIMATES OFOF CETACEANSCETACEANS ININ THE THE LIGURUIAN LIGURIAN SEA selected model (Kenney et al., 1997) a value of 12.1kg d-1 the highest of any of the four species that were present in both was obtained. The annual consumption rate was estimated to seasons and was significant (Z-test=4.35, p<0.0001). be 103kg km-2 (CV=65.3%): 5kg of fish; and 98kg of The maximum length of Mediterranean fin whales was cephalopods (Table 3). 20m, with no clear difference between males and females (from 68 stranded individuals; F. Dhermain, GECEM and O. Pilot whale Van Canneyt, CRMM, CRMM pers.- University comm.). of The La average Rochelle, weights pers. Most of the sightings of pilot whales occurred at comm.).computed The from average the Trites weights and Paulycomputed (1998) from regressions the Trites were and perpendicular distances of less than 800m; therefore a Pauly31.4t for(1998) males regressions and 30.8t forwere females, 31.4t for and males the average and 30.8t for thefor uniform model was adopted, considering that all animals females,species was and 31.1tthe average (Table for 2). the species was 31.1t (Table 2). were detected up to 800m from the transect. The species was The seasonal biomass densities correspond to 429kg km-2 encountered in summer only, with a mean school size of (CV=19.2%) in April-September and 54kg km-2 (CV=46.3%) 28.4 (CV=28.0%). The density was estimated as 0.027 in October-March (Fig. 3). The average daily ration for a fin individuals km-2 (CV=49.1%). whale was estimated to range from 393 to 680kg d-1 (1.3- Maximum lengths of Mediterranean pilot whales were 2.2% of body mass; Table 2) and computed to be 410kg d-1 600cm from 31 males and undetermined individuals and from the selected model. The annual consumption rate was 500cm from 20 females (F. Dhermain, GECEM and O. Van estimated to be 1,163kg km-2 (CV=25.2%): 1,150kg of Canneyt, CRMM CRMM, - University pers. comm.). of La Rochelle, The average pers. comm.). weights crustaceans; and 13kg of fish (Table 3). Thecomputed average from weights the Trites computed and Pauly from (1998) the Trites regressions and Pauly were (1998)689kg regressions and 451kg, were respectively, 689kg and and 451kg, the respectively, average for and the All cetacean species thespecies average was for 546kg the species (Table 2).was 546kg (Table 2). For all odontocetes combined, the biomass densities varied The summer biomass density was 14.7kg km-2 between 38.9kg km -2-2 (CV=19.2%)(CV=19.2%) in in winter winter and and 79.8kg 79.8kg km km-2- (CV=49.1%) (Fig. 3). The average daily ration for pilot whales (CV=14.5%)2 (CV=14.5%) in in summer. summer. The The total total cetacean cetacean biomass was estimated from the four models to range from 15.5 to densities were 93.4kg km-2 (CV=28.2%) in winter and 34.2kg d-1 (2.8-6.3% of body mass, Table 2), with an estimate 509.0kg km-2 (CV=16.3%) in summer. These seasonal from the selected model of 23.6kg d-1. The annual values were significantly different (Z-test=4.9, p<0.0001). consumption rate was estimated to be 116kg km-2 The combined daily food consumption of all cetaceans (CV=69.4%): 110kg of cephalopods; and 6kg of fish (Table 3). was estimated to be 2.9kg km-2 d-1 (CV=28.2%) in winter (Table 3), dominated by cephalopods (45.9%), followed by Sperm whale fish (31.3%) and crustaceans (22.8%). In summer, daily Sperm whale visual sightings and distinct acoustic consumption increased to 10.4kg km-2 d-1 (CV=16.3%), sequences represented a total of 27 encounters, including 20 strongly dominated by crustaceans (54.9%) and followed by detected only acoustically and 7 using both methods. Mean cephalopods (26.3%) and fish (18.7%). The seasonal school size was 1.5 (CV=10.5%) in summer and 3.0 difference in prey types is driven by the different densities (CV=29.6%) in winter. Their extrapolated density varied of fin whales. Annual food requirement represents 2.4t km-2 between 3.9x10-4 individuals km² (CV=39.1%) in April- (CV=20%) (Table 3, Fig. 4). September and 5.2x10-4 (CV=38.6%) in October-March, the smallest seasonal difference of any of the five species, with no significant difference (Z-test=0.52, p>0.60). The maximum length of sperm whales stranded along the French Mediterranean coast was 15m from 18 males and undetermined individuals (F. Dhermain, GECEM and O. Van Canneyt, CRMM, CRMM pers.- University comm.). of This La length Rochelle, was pers. also comm.).greater than This 30 length length was estimates also greater based than on 30 inter-pulse length estimates interval basedmeasurements on inter-pulse from acoustic interval recordings measurements in the from northwestern acoustic recordingsMediterranean in the Sea northwestern (Drouot et al. Mediterranean, 2004). The averageSea (Drouot male etweight al., 2004). computed The average from male the Tritesweight andcomputed Pauly from (1998) the Tritesregression and Pauly was 16.1t.(1998) Asregression only one was female16.1t. As length only wasone femaleavailable, length the averagewas available, female the weight average of 10.1tfemale reported weight byof 10.1tTrites reported and Pauly by (1998)Trites and was Pauly used. (1998) The average was used. for The the average for the species was 12.5t (Table 2). species was 12.5t (Table 2). Fig. 4. Annual consumption rate (kg km-2 y-1) by cetaceans in the Ligurian -2 The seasonal biomass densities were 4.9kg km Sea compared to 2000-2005 average fishery landings and production (CV=39.1%) and 6.6kg km-2 (CV=38.6%), in April-September reported for Sardinia (FAO area 1.3) and the entire Mediterranean and and October-March respectively (Fig. 3). The average daily Black Sea. ration for sperm whales was estimated to range from 189 to 393kg d-1 (1.5-3.1% of body mass, Table 2). The daily ration estimated from Kenney et al. (1997) model was 244kg d-1. The Compared to reported fishery landings from either the annual consumption rate was estimated to be 41kg km-2 whole Mediterranean Sea or only the Sardinia region, (CV=39.2%): 37kg of cephalopods; and 4kg of fish (Table 3). cetacean predation rates on crustaceans and molluscs are much larger than fishery harvest rates (Fig. 4). Competition Fin whale for molluscs between cetaceans and humans is even lower An esw of 1,152m (CV=10.3%) was estimated for fin whales, than apparent from the data because most of the species using a hazard-rate model without adjustment and after consumed by teuthophageous odontocetes, particularly large truncation at 2,000m. Mean school size was 1.6 (CV=8.1%) ones (Astruc, 2005), are not commercial species. Cetacean in April-September and 1.1 (CV=11.1%) in October-March. consumption of fish is much closer to fish (including sharks) The maximum density was observed in summer with 0.014 harvest rates reported for the Sardinia area (202kg km-2) or individuals km-2 (CV=19.2%), against 0.002 (CV=46.3%) in for the entire Mediterranean and Black Sea (437kg km-2 or winter. The 8-fold difference between seasonal densities was 487 considering aquaculture). 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 37

J. CETACEANCETACEAN RES. MANAGE. MANAGE. 11(1):31–11(1):31–40,40,­­ 2010 2009 37 Primary production required northwest Atlantic are known to be most abundant in waters The primary production required to support total prey of the continental slope and farther offshore (Waring et al., consumption by cetaceans was estimated to be 12.6gC m-2 2008), but the surveys reported by Kenney et al. (1985) were y-1. In the Ligurian Sea, the mean primary production has almost entirely inshore of the shelf break. been estimated at 165gC m-2 y-1, from SeaWiFS remotely The estimated densities for the less common species (sperm sensed imagery from 1998 to 2001 (Bosc et al., 2004). PPR whales, pilot whales and Risso’s dolphins) must be considered for cetaceans is 7.6% of that value. Total annual productivity with some caution, and the CVs are substantially larger in estimates from in situ 14C methods have varied from 86 to most cases. For sperm whales, the annual encounter rate of 226gC m-2 y-1 (Marty and Chiavérini, 1999), of which the individuals was estimated to be 0.012 individuals km-1 primary production requirement for cetaceans represents (CV=55.0%), close to previous values; 0.006 individuals per between 5.6 and 14.7%. km (CV=44.0%; Gannier, 2006) or 0.007 (CV=21.7%; Gannier et al., 2002) estimated in the same area. The estimated densities of 5.2×10-4 individuals km-2 (CV=38.6%) in winter DISCUSSION and 3.9×10-4 (CV=39.1%) in summer obtained in this study This study estimates for the first time the seasonal could only be compared with the rough estimate of 10×10-4 by variability of density and biomass of cetaceans in the Gannier (1995), which considered visual sightings only. The Ligurian Sea, as well as their rates of prey consumption and wide arbitrary distance (13km), on both sides of the transect, trophic effects. Although the results are sensitive to many to account for hydrophone efficiency may have led to an input parameters and assumptions, these results allow basic underestimate of sperm whale density and is a factor that must comparisons in order of magnitude with reported fishery be better quantified for future work. For Risso’s dolphins, the landings and phytoplankton production. A recent document few existing estimates vary over the year from 0.015 from the European Community (COM, 2003) concluded individuals km-2 (CV=60.6%) for the central Spanish that despite an increase of the fishing effort in the Mediterranean (Gómez de Segura et al., 2006) to 0.021 Mediterranean Sea overall production and rates have been (CV=37.1%) for the northwestern Mediterranean Sea steadily decreased compared to the past. The approach (Gannier, 1995). An estimated annual average of 0.023 allows better quantification of the trophic importance of individuals km-2 (CV=65.3%) was obtained in this study, cetaceans in the area and their fish demand than has been which is similar. There was a strong seasonal variation, with available in the past. winter density three times summer density, showing the migratory behaviour of Risso’s dolphin in the area. For pilot Density whales, the obtained sighting rate of 0.043 individuals km-1 Both seasonal sampling periods were covered by more than (CV=49.1%) between April and September is quite low when 2,000km of survey effort, including at least 12 surveys over compared to the value of 0.14 whales km-1 (CV=69.3%) the 4 years. The estimated densities for the two most obtained in the area in July-August 2001 (Gannier, 2006). common species, striped dolphin and fin whale, should be However the latter result was based on only a single sighting, considered as reliable, which is supported by CVs of <22% and both estimates have large variances. The estimated except for fin whales in winter. The estimate of summer fin summer density (0.027 individuals km-2; CV=49.1%) is whale density (0.014 individuals km-2; CV=19.2%) is in almost identical to the 0.028 (CV=62.3%) value computed agreement with previous results, which vary from 0.015 from the results of Gannier (1995). individuals km-2 (CV=15.9%; Gannier, 1997) in the Liguro- Provençal area to 0.024 individuals km-2 (CV=27.0%; Biomass and food consumption Forcada et al., 1996; Gannier, 1997) in the western Prior to the first dedicated surveys for cetaceans in the Mediterranean Sea. Fin whale density in the Ligurian Sea is Mediterranean Sea in the 1990s, biomasses of the eight most also similar to other regions of the North Atlantic, with 0.021 common species were roughly estimated for the area between individuals km km-2-2 to to 0.053 0.053 (Buckland (Bucklandet et al. al,., 1992; 1992; Kenney Kenneyet 40°N and European coasts (300,000km2) (table 13 in Viale, al.et ,al 1985).., 1985) Previous Previous estimates estimates ofof thethe summersummer density of of 1985). Interestingly, beginning from mean body mass striped dolphins in the area ranged between 0.30 individuals estimates that varied substantially from the values used in this km-2 (CV=35%) and 0.75 (Forcada and Hammond, 1998; study and approximate numbers of animals in the area (with Gannier, 2006), with the minimum estimated just after an no clear details available on those estimates), the author epizootic mortality event. The estimate of 0.87 individuals calculated a total cetacean biomass of 86,950t, representing a per km-2 (CV=15.2%) in April-September period is in biomass density of 290kg km-2, very close to the estimate agreement, considering that previous estimates were obtained in this study (300kg km-2). In addition, Viale (1985) conducted in July and/or August, while in the data set used in estimated fish consumption of 58,100t, corresponding to this study surveys were also carried out in September, which 194kg km-2, while a value of 522 kg km-2 was obtained in this corresponds to the maximum occurrence of striped dolphins study. For cephalopods her results corresponded to 763kg in the area (Laran and Drouot-Dulau, 2007). In the central km-2, and for macro- and microzooplankton, 1,100kg km-2, Spanish Mediterranean Sea, a maximum seasonal abundance while estimates of 739 and 1,160kg km-2 respectively were of 0.60 individuals per km-2 (CV=26.0%) was recorded in obtained here. Since the methods and input parameters were Autumn (Gómez de Segura et al., 2006) – this is a well- completely independent, this level of agreement is somewhat known productivity area (e.g. Cañadas and Hammond, encouraging. The better-supported estimates obtained through 2006). These estimates are higher than the maximum density this study, using better density values, also identify variations estimate for any sampling stratum in the northwest Atlantic between warm and cold seasons. (0.37 individuals per km-2; Kenney et al., 1985) or for small delphinids in the Bay of Biscay (0.55 individuals per km-2, Comparisons with different studies and locations CV=29%; Certain et al., 2008), however both studies were The Mediterranean Sea, a semi-enclosed sea, has a lower based on aerial surveys and for the northwest Atlantic a much cetacean diversity than many other areas. Along the US higher proportion of small delphinid sightings was not western coast, for example, about twenty cetacean species are identified to species. In addition, striped dolphins in the observed in the Californian Current ecosystem (Barlow et al., 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 38

38 LARAN et al.:.: SEASONAL ESTIMATESESTIMATES OFOF CETACEANSCETACEANS ININ THE THE LIGURUIAN LIGURIAN SEA 2008). Thirty-five species of cetaceans are known to occur The primary production required for cetaceans was along the eastern coast of the US (Waring et al., 2008). estimated as 20-30gC m-2 y-1 in the Pacific Ocean (Trites et Estimates of biomass densities and prey consumption rates al., 1997), 31.4gC m-2 y-1 in the California Current ecosystem allow for more informative comparisons with other areas than (Barlow et al., 2008) and 47.5gC m-2 y-1 in the northeastern is possible using only species abundances or densities. The US shelf ecosystem (Kenney et al., 1997), all higher than the estimate of annual average biomass density obtained in this estimate of 12.6 obtained here. The mathematical model used study (301kg km-2) is intermediate between 143kg km-2 for to estimate PPR (Eqn. 8) includes a power function, so the marine mammals in the entire Pacific Ocean (Trites et al., PPR estimates are especially sensitive to the trophic level of 1997) and 729kg km-2 for cetaceans only in the northeastern the prey species and the most difficult result to compare US continental shelf system (Kenney et al., 1997). During between ecosystems. ecosystems. Following Following Barlow Barlowet et al al. (2008),. (2008), whom who summer and autumn, Barlow et al. (2008) estimated a value of conducted sensitivity analysis in a similar study in the 282kg km-2 for cetacean biomass density in the California California area, the main effect on approximation of result is current ecosystem, with a proportion of Balaenopteridae the energy transfer across the food web. (70%) similar to the observations noted in this paper. Seasonal variability was somewhat stronger in the Ligurian Sea than in Potential sources of variability and error the NE US shelf; the results detailed here differ by a factor of In the area used in this study, further investigation is five between six-month winter and summer seasons, while necessary to derive more reliable density estimates for less Kenney et al. (1997) reported a maximum ratio of 3.8 between common species such as sperm whales, pilot whales and winter and spring. In agreement with the results of the study Risso’s dolphins, in addition to the rarer or coastal species that presented here and those of Barlow et al. (2008), Kenney et al. were not sampled at all during the surveys. In addition, there (1997) showed a cetacean community dominated by is a negative bias caused by not considering g(0). For the fin balaenopterids, at 72-78% of the total standing stock, but their whale, no decrease in detection probability on the line was dominance continued through all four seasons of the year. recorded between fast and reduced-speed sampling (22 and TheThe point estimate of of food food intake intake by by cetaceans cetaceans (2.4t (2.4t km km-2 y-2-1 13km h-1), in contrast with the striped dolphin for which a iny-1 thisin this study) study) is is much much greater greater than than results results for for northern decrease of 12% was estimated at 22km h-1 (Laran, 2005). European seas, ranging between 0.25t km-2 y-1 in Atlantic Therefore there was probably an underestimation of striped waters to 0.75 around Spitsbergen and in polar waters dolphin density. For the sperm whale, acoustic sampling (Joiris, 1992; 1996; 2000). Prey consumption estimates allowed detection of clicks during almost all their dive from the studies discussed immediately above, as expected, durations (Mullins et al., 1988), but the efficiency of the follow the same order as the estimates of biomass density. hydrophone likely varies with water column conditions, Barlow etet al al.. (2008)(2008) reported reported consumption consumption of of 1.5-2.4t 1.5-2.4t km km-2 y-2-1 instead of remaining constant at the arbitrary sampling width iny-1 thein theCalifornia California current, current, the the most most similar similar value value to to that that of of 13km. In addition, the sampling protocol allowed monthly this study; the minimum was 0.84t km-2 y-1 in Pacific Ocean effort to be maintained during three years, but was not suited (Trites et al., 1997) and the maximum was 6.7t km-2 y-1 on to estimation of cetacean abundance in the entire Pelagos the northeastern US continental shelf (Kenney et al., 1997). Sanctuary. Additional field campaigns over broader areas of Estimates of fish consumption by marine mammals vary the Sanctuary, dedicated to abundance estimation, should be from 0.10t km-2 y-1 in the North Sea to 5.4t km-2 on Georges carried out in summer and winter to obtain accurate estimates. Bank (Bax, 1991), and the point estimate obtained here of Previous studies of this type (Kenney et al., 1985; Kenney 0.48t km-2 y-1 of fish consumed corresponds to the lower et al., 1997; Sigurjónsson and Víkingsson, 1997; Trites and end of that range. Kenney et al. (1997) estimated fish Pauly, 1998) generally have relied on relatively imprecise consumption to to be be an an order order of ofmagnitude magnitude higher higher at 4.6t at 4.6t km-2 km y-1- estimates of body mass available from the literature as the because2 y-1 because the dietthe diet of fin,of fin, humpbackhumpback and and minke minke whales whales off off starting point for bioenergetic models. Kenney et al. (1985) the northeastern US is primarily fish rather than crustaceans. had reliable data from their own study area for only one WorldWorld fisheryfishery catch catch rates rates vary vary between between 10 and 10 22.2tand 22.2t km-2 species, using a set of photogrammetric length measurements kmy-1 -2(from y-1 (from oligotrophic oligotrophic open-ocean open-ocean systems systems to to highly highly of fin whales and a published weight-length equation to productive upwellings) representing 1.8-35% of the total net derive a mean weight for the study region. Trites and Pauly primary production (Pauly and Christensen, 1995). (1998) have assisted researchers developing marine mammal Compared with commercial fisheries, the point estimate of energetic models by presenting estimates of average body the relative proportion of fish consumed by marine mammals weights for all species, although they did not provide represents some 2% of the fisheries in the North Sea (Bax, estimates of variability. Finally, using maximum lengths 1991), 167% in the Barents Sea (Bax, 1991) and 171% in the observed within a particular area, when available, enables the northeastern US shelf (Kenney et al., 1997). About 150% modelling results to better represent the local or regional was estimated for herring only in the Gulf of Maine system. Large datasets of body weights from a particular (Overholtz and Link, 2006). In the Ligurian Sea, the point region would allow direct estimation of mean weights and estimate of the proportion of fish consumed by cetaceans variability, although it becomes more difficult with represents 257% of the reported fishery if only the Sardinia increasing body size and there are concerns over bias if the area is considered and 107% compared to global production data are obtained from strandings. of fisheries (i.e. catches and aquaculture combined) from the Another important source of uncertainty in the results is entire Mediterranean Sea. Since a large proportion of the fish prey consumption rate. The mean daily rations estimated as harvested remains unrecorded, relative percentages of percentages of an individual’s body mass (1.3-6.7% using cetacean consumption should probably be reduced compared the selected model and 1.3-9.1% across all four models) are to actual catches. In the Pacific Ocean, Trites et al. (1997) consistent with general approximations of 3 to 5% for estimated that fisheries target only 35% of the prey items marine mammals (Trites, 2003). The model used here was sought by marine mammals. However this ratio could vary intermediate in value, and was the model proposed by between predator species; for example 70% of the total prey Barlow et al. (2008) to be the most realistic. Fin whale daily species of striped and Risso’s dolphins in the Mediterranean intake has been estimated as 1.3-3.3% of body mass from are commercial species (Würtz et al., 1992). various methods (Lockyer, 1981; 2007), but the estimates 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 39 031-040 JNL 374:Layout 1 29/12/09 14:11 Page 39

J. CETACEANCETACEAN RES. MANAGE. MANAGE. 11(1):31–11(1):31–40,40,­­ 2010 2009 39 generally are based on very low or no feedingJ. CETACEAN duringwinter RES. MANAGE.Aubouin,Aubouin,11(1):31–40, J. J. and and Durand-Delga, Durand-Delga, 2009 M. M. 2002. 2002. Bathymetrie Bathymetrie et et nomenclature nomenclature des des39 bassins et reliefs. pp.717-19. In:: Doumenge, F., Aubouin, J. and and Durand- Durand- and higher rates in summer to compensate. The rate of 1.3% Aubouin, J. and Durand-Delga,In M. 2002. Bathymetrie et nomenclature des generally are based on very low or no feeding during winter Delga, M. (eds). Méditerranée (Mer). Vol. 14, 14, Encyclopedia Encyclopedia Universalis Universalis,, andobtained higher during rates in the summer study to described compensate. here The represents rate of 1.3% the Paris,bassins France. France. et reliefs. pp.717-19. In: Doumenge, F., Aubouin, J. and Durand- Delga, M. (eds). , lower end of the range, but increased feeding in summer to Baird,Baird, R.W., R.W., Fabrizio FabrizioMéditerranée Borsani, Borsani, J., J., Bradley (Mer). Bradley Vol. Hanson, Hanson, 14, Encyclopedia J. and and Tyack, Universalis P.L. P.L. 2002. 2002. obtained during the study described here represents the Paris, France. account for lower consumption during winter was not Diving and night-time behaviour of long-finned pilot pilot whales whales in in the the lower end of the range, but increased feeding in summer to Baird, R.W., Fabrizio Borsani, J., Bradley Hanson, J. and Tyack, P.L. 2002. Ligurian Sea. Marine Ecology. Progress Series 237237:: 301-05. 301-05. Note. Note. considered. Although fin whales have been observed Diving and night-timeMarine Ecology. behaviour Progress of long-finned Series pilot whales in the account for lower consumption during winter was not Barlow,Barlow, J., J., Kahru, Kahru, M. M. and and Mitchell, Mitchell, B.G. B.G. 2008. 2008. Cetacean Cetacean biomass, biomass, prey feeding in winter in the Mediterranean (Canese , 2006), Ligurian Sea. 237: 301-05. Note. considered. Although fin whales have beenet al. observed consumptionconsumption andMarine and primary primary Ecology. production production Progress requirements requirements Series in in the the California California Barlow, J., Kahru, M. and Mitchell, B.G. 2008. Cetacean biomass, prey itfeeding is believed in winter that in theythe Mediterranean feed very little (Canese or not at, all 2006), and Current ecosystem. Mar. Ecol. Prog. Ser. 371:371: 285-95. 285-95. et al. consumption and primaryMar. Ecol. production Prog. Ser. requirements in the California therefore must increase their summer feeding rate. Barros,Barros, N.B. and and Clarke, Clarke, M.R. 2002. Diet. pp.323-27. In:: Perrin, W.F., it is believed that they feed very little or not at all and Current ecosystem. 371: 285-95. In Würsig, B. and Thewissen,Mar. Ecol. J.G.M. Prog. Ser. (eds). (eds). Encyclopedia of Marine thereforeFor many must marine increase mammal their summer species, feeding Pauly rate.et al. (1998) Barros, N.B. and Clarke, M.R. 2002. Diet. pp.323-27.Encyclopedia: Perrin, of Marine W.F., Mammals.. Academic Academic Press, Press, San San Diego. Diego. In estimated proportions of their diets comprised of eight Würsig,Mammals B. and Thewissen, J.G.M. (eds). For many marine mammal species, Pauly et al. (1998) Bax,Bax, N. N. 1991. 1991. A comparison of the fish biomassbiomassEncyclopedia flowflow to to fish, fish, fisheries offisheries Marine and and estimateddifferent prey proportions categories of their (benthic diets invertebrates,comprised of eightlarge mammalsMammals. in Academic six marine Press, ecosystems. San Diego. 193: 217-24. Bax,mammals N. 1991. in Asix comparison marine ecosystems. of the fish ICES biomass Mar. flow Sci. Sci. toSymp Symp. fish,. 193: fisheries 217-24. and differentzooplankton, prey small categories squid, large (benthic squid, smallinvertebrates, pelagic fishes, large Bearzi,Bearzi, G. G. 2002. 2002. Interactions between cetaceans cetaceans and fisheries in in the the mesopelagic fishes, miscellaneous fishes and higher mammalsMediterranean in six Sea.marine pp.20. ecosystems.: NotarbartoloICES Mar. Sci. di Symp. Sciara,193: G. 217-24. (eds). zooplankton, small squid, large squid, small pelagic fishes, Bearzi,Mediterranean G. 2002. Sea. Interactions pp.20. betweenInIn: Notarbartolo cetaceans di and Sciara, fisheries G. in (eds). the mesopelagicinvertebrates).fishes, However miscellaneous their estimates representfishes and worldwide higher CetaceansMediterranean of the Sea.Mediterranean pp.20. and: Notarbartolo Black Seas: Seas: state di Sciara,of knowledge G. (eds). and and conservationconservation strategies strategies.. A A report reportIn to to the the ACCOBAMS ACCOBAMS Secretariat, Secretariat, averages, do not includes estimates of variability and are Cetaceans of the Mediterranean and Black Seas: state of knowledge and invertebrates). However their estimates represent worldwide Monaco, February 2002. 2002. averages,themselves do based not includes on relatively estimates sparse of variability data. Additional and are Bosc,conservation E., Bricaud, strategies A. and.Antoine, A report D. to 2004. the ACCOBAMS Seasonal and Secretariat,interannual Bosc,Monaco, E., Bricaud, February A. 2002. and Antoine, D. 2004. Seasonal and interannual themselvesdetailed information based on on relatively diet composition sparse data. specific Additional to the variability in in algal algal biomass biomass and and primary primary production production in in the the Mediterranean Mediterranean Bosc,Sea, E., as Bricaud, derived A. from and 4 Antoine, years of D. SeaWIFS2004. Seasonal observations. and interannual detailedLigurian informationSea is required on to diet improve composition consumption specific estimates to the Sea,variability as derived in algal frombiomass 4 and years primary of SeaWIFS production observations. in the Mediterranean GlobalGlobal Biogeochemical Cycles Cycles 18:18: 1-17. 1-17. Ligurianfor individual Sea is prey required categories to improve and to better consumption assess variability. estimates Sea, as derived from 4 years of SeaWIFS observations. Global Bowen,Bowen, W.D. W.D. 1997. 1997. Role Role of of marine marine mammals mammals in aquatic ecosystems. Mar. For pilot whales and Risso’s dolphins only a few results are Biogeochemical Cycles 18: 1-17. for individual prey categories and to better assess variability. Ecol. Prog. Ser Ser.. 158:158: 267-74. 267-74. Bowen, W.D. 1997. Role of marine mammals in aquatic ecosystems. Mar. Foravailable pilot whales for the and Mediterranean Risso’s dolphins Sea, and only we a few recognise results that are Buckland,Buckland, S.T., S.T., Anderson, Anderson, D.R., D.R., Burnham, Burnham, K.P., Laake, Laake, J.L., Borchers, Borchers, our conclusions could vary greatly based on new and better D.L.Ecol. Prog. and Thomas, Ser. 158: 267-74.L. 2001. available for the Mediterranean Sea, and we recognise that Buckland,D.L. and S.T., Thomas, Anderson, L. 2001.D.R., Burnham,IntroductionIntroduction K.P., to to Laake, Distance Distance J.L., Sampling: Sampling: Borchers, information. Striped dolphins feed on a variety of pelagic Estimating Abundance Abundance of Biological Populations.. Oxford Oxford University University our conclusions could vary greatly based on new and better Press,D.L. andOxford, Thomas, UK. vi+xv+432pp. L. 2001. Introduction to Distance Sampling: and benthopelagic fish and squid (Archer, 2002). Pauly et al. Press,Estimating Oxford, Abundance UK. vi+xv+432pp. of Biological Populations. Oxford University information. Striped dolphins feed on a variety of pelagic Buckland,Buckland, S.T., S.T., Cattanach, Cattanach, K.L. K.L. and and Gunnlaugsson, Gunnlaugsson, T. T. 1992. 1992. Fin whale and(1998) benthopelagic described their fish diet and as squid 5% (Archer, benthic invertebrates, 2002). Pauly 20% abundancePress, Oxford, in the UK. North vi+xv+432pp. Atlantic, estimated from Icelandic and Faroese et al. Buckland,abundance S.T., in the Cattanach, North Atlantic, K.L. and estimated Gunnlaugsson, from Icelandic T. 1992. and Fin Faroese whale (1998)small squid, described 15% their large diet squid, as 5% benthic 5% small invertebrates, pelagics, 30%20% NASS-87 and and NASS-89 NASS-89 data. data. Rep.Rep. int. int. Whal. Whal. Commn Commn 42:42: 645-51. 645-51. mesopelagics and 25% miscellaneous or 60% fish, 35% Cañadas,abundance A. and in the Hammond, North Atlantic, P.S. 2006. estimated Model-based from Icelandic abundance and estimates Faroese small squid, 15% large squid, 5% small pelagics, 30% Cañadas,NASS-87 A. and Hammond, NASS-89 data. P.S. Rep.2006. int. Model-based Whal. Commn abundance42: 645-51. estimates squid and 5% invertebrates, as compared with the values forfor bottlenose bottlenose dolphins dolphins off off southern southern Spain: Spain: implications implications for for conservation conservation mesopelagics and 25% miscellaneous or 60% fish, 35% Cañadas,and management. A. and Hammond, P.S. 2006. Model-based8(1): 13-27. abundance estimates used in this study of 49.3% fish, 49.7% squid and 1% andfor bottlenosemanagement. dolphins J.J. Cetacean Cetacean off southern Res. Res. Manage Manage. Spain:. implications 8(1): 13-27. for conservation squid and 5% invertebrates, as compared with the values Canese,Canese, S., S., Cardinali, Cardinali, A., A., Fortuna, Fortuna, C.M., C.M., Giusti, Giusti, M., M., Lauriano, Lauriano, G., Salvati, crustaceans. In the Ligurian Sea they exploit many mid- E.and and management. Greco, S. 2006.J. Cetacean The first Res. identified Manage. winter8(1): feeding13-27. ground of fin used in this study of 49.3% fish, 49.7% squid and 1% Canese,E. and S.,Greco, Cardinali, S. 2006. A., Fortuna,The first C.M., identified Giusti, winter M., Lauriano, feeding ground G., Salvati, of fin crustaceans.water species In (Würtz the Ligurian and Marrale, Sea they 1993). exploit The many few winter mid- whales ( Balaenoptera physalus )) in in the the Mediterranean Mediterranean Sea. J. Mar. Biol. Biol. E. and Greco,86: 903-07. S. 2006. The first identified winter feeding ground of fin samples analysed from the Ligurian Sea suggest that they AssAss.. UK. 86: 903-07. water species (Würtz and Marrale, 1993). The few winter Certain,whales G., (Balaenoptera Ridoux, V., physalus van Canneyt,) in the Mediterranean O. and Bretagnolle, Sea. J. Mar. V. 2008. Biol. may feed at times in winter on cephalopods alone (G. Astruc Certain, G., Ridoux, V., van Canneyt, O. and Bretagnolle, V. 2008. samples analysed from the Ligurian Sea suggest that they DelphinidAss. UK. 86: spatial 903-07. distribution and abundance estimates over the shelf of Delphinid spatial distribution and abundance estimates over the shelf of and D. Agati, pers. comm.). The stable-isotope analyses Certain,the Bay G., of Biscay.Ridoux, V., van Canneyt,65(4): O. 656-66.and Bretagnolle, V. 2008. may feed at times in winter on cephalopods alone (G. Astruc the Bay of Biscay. ICESICES J. J. Mar. Mar. Sci Sci.. 65(4): 656-66. developed for several species in the area could also help to Clarke,Delphinid A. and spatial Prince, distribution P.A. 1980. and Chemical abundance composition estimates and over calorific the shelf value of and D. Agati, pers. comm.). The stable-isotope analyses Clarke, A. and Prince, P.A. 1980. Chemical composition and calorific value ofthe food Bay fed of Biscay. to mollymaukICES J. chicks Mar. Sci.at Bird65(4): Island, 656-66. South Georgia. 122: better quantify and refine cetacean diets and interannual of food fed to mollymauk chicks at Bird Island, South Georgia. IbisIbis 122: developed for several species in the area could also help to Clarke,488-94. A. and Prince, P.A. 1980. Chemical composition and calorific value variability in diet, and stable-isotope studies on particular 488-94. better quantify and refine cetacean diets and interannual Clarke,of food M.R., fed toMartins, mollymauk H.R. andchicks Pascoe, at Bird P. Island, 1993. The South diet Georgia. of spermIbis whales122: Clarke, M.R., Martins, H.R. and Pascoe, P. 1993. The diet of sperm whales variabilityprey species in would diet, and enable stable-isotope more precise studies estimates on particular of the (488-94. Linnaeus 1758) off the Azores. Clarke,(Physeter M.R., macrocephalus Martins, H.R. Linnaeus and Pascoe, 1758) P. 1993. off the The Azores. diet of Philos. sperm whalesTrans. preytrophic species levels would of prey enable for morePPR calculations. precise estimates Meanwhile of the R. Soc. Lond. B. (Biol. Sci.) 339(1287): 67-82. R.(Physeter Soc. Lond. macrocephalus B. (Biol. Sci.)Linnaeus 339(1287): 1758) 67-82. off the Azores. Philos. Trans. trophicaccurate levels estimate estimate of of prey of numerous numerous for parameters parameterscalculations. in in the Meanwhile the area area and a COM. 2003. Proposal for a Council Regulation concerning management PPR COM.measuresR. Soc. 2003. Lond. for Proposal B. the (Biol. sustainable for Sci.) a Council339(1287): exploitation Regulation 67-82. of concerningfishery resources management in the accuratebetter quantification estimate of of numerous their variability parameters is important in the to area better a COM.measures 2003. for Proposal the sustainable for a Council exploitation Regulation of fishery concerning resources management in the quantify CVs associated with cetacean consumption Mediterranean Sea and amending regulations (EC) No. 2847/93 and (EC) better quantification of their variability is important to better MediterraneanNo.measures 973/2001. for theSea Commission sustainableand amending of exploitation the regulations European of(EC) Communities, fishery No. 2847/93 resources Brussels, and in (EC) the 9 quantifyestimated in CVs the area. associated with cetacean consumption No.OctoberMediterranean 973/2001. 2003, COM(2003) Sea Commission and amending 589 of final the regulations European2003/0229 (EC) Communities, (CNS). No. 2847/93 39pp. Brussels, and (EC) Croxall,9No. October 973/2001. J.P. 2003, and Prince, Commission COM(2003) P.A. 1982. of589 the final Calorific European 2003/0229 content Communities, (CNS). of squid 39pp. Brussels, (Mollusca: 9 estimated in the area. Croxall,October J.P. 2003, and Prince, COM(2003) P.A. 1982. 589 final Calorific 2003/0229 content (CNS). of squid 39pp. (Mollusca: Cephalopoda). Br. Antarct. Surv. Bull. 55: 27-31. ACKNOWLEDGEMENTS Drouot,Croxall,Cephalopoda). V., J.P. Gannier, and Br. Prince, Antarct. A. and P.A. Goold, Surv. 1982. Bull J. Calorific 2004.. 55: 27-31. Diving content and of feeding squid (Mollusca: behaviour Drouot,Cephalopoda). V., Gannier, A. and Goold, J. 2004.55: Diving 27-31. and feeding behaviour of sperm whalesBr. Antarct. (Physeter Surv. macrocephalus Bull. ) in the northwestern TheACKNOWLEDGEMENTS survey programme was supported by Marineland, Drouot,of sperm V., Gannier, whalesA. (Physeter and Goold, macrocephalus J. 2004. Diving) and in thefeeding northwestern behaviour Mediterranean Sea. Aquat. Mamm. 30: 419-26. ThePELAGOS survey programme Sanctuary was (the supported French by Ministry Marineland, of Estes,Mediterraneanof J.A.,sperm DeMaster, whales Sea. Aquat. D.P., (Physeter Doak, Mamm D.F., macrocephalus. 30: Williams, 419-26. T.M.) in and the Brownell, northwestern R.L., The survey programme was supported by Marineland, Estes,Mediterranean J.A., DeMaster, Sea. D.P.,Aquat. Doak, Mamm. D.F.,30: Williams, 419-26. T.M. and Brownell, R.L., PELAGOS‘Environnement Sanctuary et Développement (the French Durable’). Ministry We thanks ofS. Jr. 2006. Whales, Whaling and Ocean Ecosystem. University of PELAGOS Sanctuary (the French Ministry of Estes,Jr.California 2006.J.A., DeMaster, Press,Whales, Berkeley, D.P., Whaling Doak, California. and D.F., Ocean Williams, 402pp. Ecosystem T.M. and. Brownell, University R.L., of ‘EnvironnementBourreau and all et Développementthe observers who Durable’). participated We thanks to the S. CaliforniaJr. 2006. Press, Berkeley, California. 402pp. . University of ‘Environnement et Développement Durable’). We thank FAO. 2008. FisheryWhales, statistics Whaling programme and Ocean. Food and Ecosystem Agriculture Organization surveys: V. Drouot., T. Bonniard, S. Jérémie, S. Bonnet., A. FAO.California 2008. Fishery Press, statistics Berkeley, programme California.. Food 402pp. and Agriculture Organization BourreauS. Bourreau and and all all the the observers observers who who participated participated to to the of the United Nations, Rome. [http://www.fao.org/fishery/topic/16073]. surveys:Littaye., V. M.V. Drouot, Drouot., Fermon, T. Bonniard, T. E. Bonniard, Poncelet, S. Jérémie, S.I. Brasseur., Jérémie, S. Bonnet, S. A. Bonnet., Malmezat, A. Littaye, A. Farrugio,FAO.of the 2008. United H.,Fishery Olivier, Nations, statistics P. Rome. and programme Biagi, [http://www.fao.org/fishery/topic/16073 F. 1993.. Food An and overview Agriculture of Organization the history,]. surveys: of the United Nations, Rome. [ ]. Littaye.,G.M. Fermon, Pernette, M. E. Fermon, E.Poncelet, Ricard, E. I. Poncelet, Brasseur, P. Mangion, I. A. Brasseur., Malmezat, B. Lombrail, A. G. Malmezat, Pernette, A-M Farrugio,knowledge, H., Olivier, recent and P. and future Biagi, researchhttp://www.fao.org/fishery/topic/16073 F. 1993. trends An in overview Mediterranean of the fisheries. history, Farrugio,knowledge, H.,57: Olivier,recent 105-19. and P. future and Biagi, research F. 1993. trends An in overviewMediterranean of the fisheries. history, G.MeissnerE. Ricard, Pernette, and P. Mangion,A.E. Delmas. Ricard, B. Thanks P. Lombrail, Mangion, to F. A-M Dhermain B. Meissner Lombrail, (GECEM) and A-M A. knowledge,Sci. Mar. recent and future research trends in Mediterranean fisheries. and O. Van Canneyt (CRMM) and volunteers from the French Forcada,Sci. Mar J.,. 57: Aguilar, 105-19. A., Hammond, P., Pastor, X. and Aguilar, R. 1996. MeissnerDelmas. Thanks and A. to Delmas. F. Dhermain Thanks (GECEM) to F. Dhermain and O. Van (GECEM) Canneyt Forcada,DistributionSci. Mar. J., Aguilar,57: and 105-19. abundance A., Hammond, of fin whales P., Pastor, ( X. and Aguilar, R.) 1996. in the Mediterranean stranding network (RNE), G. Astruc, and to W. Forcada, J., Aguilar, A., Hammond, P., Pastor,Balaenoptera X. and Aguilar, physalus R. 1996. and(CRMM O. Van - University Canneyt (CRMM) of La Rochelle) and volunteers and volunteers from the from French the Distributionwestern Mediterranean and abundance sea during of fin the whales summer. (BalaenopteraJ. Zool. (Lond.) physalus238:) 23- in MediterraneanOverholtzFrench Mediterranean for his stranding helpful stranding network comments network (RNE), on the(RNE), G. manuscript. Astruc, G. 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