Abundance and Distribution of Eggs and Larvae of Anchovy

Total Page:16

File Type:pdf, Size:1020Kb

Abundance and Distribution of Eggs and Larvae of Anchovy Turkish Journal of Zoology Turk J Zool (2013) 37: 773-781 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1212-31 Abundance and distribution of eggs and larvae of anchovy (Engraulis encrasicolus, Linnaeus, 1758) and horse mackerel (Trachurus mediterraneus, Steindachner, 1868) on the coasts of the eastern Black Sea 1, 2 Cemalettin ŞAHİN *, Necati HACIMURTAZAOĞLU 1 Faculty of Fisheries, Recep Tayyip Erdoğan University, Rize, Turkey 2 Republic of Turkey Ministry of Food, Agriculture, and Livestock, Trabzon, Turkey Received: 27.12.2012 Accepted: 08.07.2013 Published Online: 04.10.2013 Printed: 04.11.2013 Abstract: Sampling for this survey was performed in 5 stations located in the bays of Sürmene and Rize in the eastern Black Sea between April and October 2006. During the sampling, the quantities and distributions of eggs and larvae of anchovies (Engraulis encrasicolus) and horse mackerel (Trachurus mediterraneus) were determined. For horizontal towing carried out from the surface (0–5 m), a plankton net of 50 cm in diameter and 500 µm mesh. The eggs of anchovy and horse mackerel sampled in plankton tows were found to be 438.33 ind./100 m3 and 5.71 ind./100 m3 for horizontal tows. During horizontal tows, the larvae of anchovy and horse mackerel were found to be 8.00 ind./100 m3 and 0.68 ind./100 m3, respectively. During the surveys, a total of 14,535 anchovy eggs, 147 horse mackerel eggs, 256 anchovy larvae, and 7 horse mackerel larvae were sampled. Mortality rates were calculated as 81.18% for anchovy and 37.41% for horse mackerel. According to our results, the ranges of spawning periods for anchovy and horse mackerel were determined as May–September and June–August, respectively. Key words: Abundance, anchovy, eastern Black Sea, egg, horse mackerel, ichthyoplankton, larva 1. Introduction abundance of pelagic eggs and larvae of teleost fish in the In Turkey’s seafood products industry, anchovy and horse northern Marmara Sea (Yüksek, 1993); distribution of mackerel are ranked in the top 2 positions within the anchovy eggs and larvae in the Black Sea (Niermann et species obtained by fishing from natural resources. These al., 1994); seasonal distribution of certain teleost fishes in 2 small pelagic species of fish are the major species in the the Bay of Sürmene (Başar, 1996); distribution of fish eggs Black Sea and constitute approximately 59% of the seafood and larvae off the coast of Trabzon (Ak, 2009); the effect of production in Turkey. Anchovy and horse mackerel that are environmental conditions in the distribution of the eggs landed in the eastern Black Sea constitute 27.4% (184,417 t) and larvae of anchovies in the Black Sea (Kideys et al., and 4.1% (17,755 t) of the total marine fish catch of Turkey 1999); and ichthyoplankton of Feodosiya Bay (Klimova, (TÜİK, 2012). These species, possessing such significance 2009). in Turkey’s fishing industry, must be observed in all phases An egg survey is required in order to determine the of their life cycle in order to ensure the sustainability of spawning periods and spawning areas of the fish and the their stocks. The most important of these phases are the periodic changes taking place in these environments, ichthyoplankton phases (eggs and larvae). Slastenenko the losses in the egg and larvae phases, the ratio of entry (1956) provided significant information concerning into the adult stocks, and the number of spawning adult the spawning characteristics, egg types, and egg sizes of individuals in the stocks and their relationship with the the fish in the Black Sea for the first time. The following environment. Although there are a significant number have also been investigated: morphologies and ecologies of studies in the Black Sea in this context, egg survey of certain bony fish (teleosts) in the Marmara Sea and investigations are scant in the eastern Black Sea region. Black Sea (Arım, 1957); pelagic eggs and larvae of teleosts Along with the seasonal abundance of eggs and larvae, in Turkish waters (Demir, 1974); distribution of fish the determination of their horizontal distribution was eggs and larvae at the Black Sea entrance of the İstanbul performed in this research in order to be able to make straits (Mater and Cihangir, 1990, 1997); distribution and proper decisions about the future of the anchovy and horse * Correspondence: [email protected] 773 ŞAHİN and HACIMURTAZAOĞLU / Turk J Zool mackerel stocks, which have an economic significance for and Çoker (2002), and Çoker (2003) were utilized as the region. references. Abundances and distributions of eggs and larvae according to stations were calculated utilizing the 2. Materials and methods individual per m3 B = C / V relationship in horizontal The survey was carried out in the eastern Black Sea on tows, where B is abundance (ind./m3), C is total number of the Trabzon Sürmene, İyidere, and Rize coasts between samples in horizontal sampling, and V is volume of water April 2006 and October 2006. Samplings were performed filtered (m3). The water volume V was obtained by V = A horizontally at 5 stations (A1, A2, B1, C1, C2) using the × r × c, where A = area of net mouth (m2), r = flowmeter research vessel “R/V DENAR–1” belonging to Karadeniz rotation number, and c = flowmeter calibration rate (m / Technical University. The distances between the coastal rotation). The determination was done with a Hydro-Bios stations are 13 NM (A1–B1) and 10 NM (B1–C1), 438 115 model flowmeter (Smith and Richardson, 1977). respectively. For the offshore stations (A2–C2), the Flowmeter calibration rate was 0.3. distance is 5 NM from the coast. The depths of stations Dead eggs were determined according to Iseki were determined as 18 m, 415 m, 14 m, 15 m, and 310 m, and Kiyomoto (1997) and Yüksek and Gücü (1994) respectively (Figure 1). as abnormally developed eggs, such as those with For horizontal samplings, a 50-cm-diameter and decomposition process of the embryo, and physically 500-µm-mesh plankton net was used. Samplings were decayed eggs without categorized embryo stage and with carried out during the day at depth intervals of 0–5 m decomposition of the perivitelline layer of the eggs. by towing the net for 10–15 min at a vessel speed of 2.5 A normality test (Shapiro–Wilk) was applied to miles h–1. Temperature and salinity measurements were larvae and egg number distributions between stations conducted at stations A2 and C2 throughout the survey. and months. ANOVA for parametric and Kruskal–Wallis The temperature and salinity values were determined by analysis for nonparametric data were conducted using using equipment by Aanderaa Instruments, the RCM9 the software packages PAST (version 1.8) (Hammer et al., model CTD and YSI 85 model probe, during the uptake 2001) and Sigma Plot (version 11.0). Statistical analyses of the material. The collected material was preserved in were considerate significantly different at the level of α = 4% formaldehyde solution with a borax buffer (Smith 0.05. and Richardson, 1977). Samples of ichthyoplankton were sorted from the zooplankton material and species 3. Results identification was performed. For the determination of 3.1. Physicochemical properties of water column egg and larvae species, the works of Arım (1957), Dekhnik The maximum surface water temperature of station A2 was (1973), Russell (1976), Yüksek and Gücü (1994), Mater found to be 23.90 °C in July and the minimum was 13.80 N 41O 30' Hopa BLACK SEA C2 C1 41O B1 RİZE A2 40˚ A1 İyidere Turkey TRABZON Sürmene 40O 40O 30' 41O 41O 30' Figure 1. Sampling area. 774 ŞAHİN and HACIMURTAZAOĞLU / Turk J Zool °C in April; the maximum at station C2 was found to be 3.2.1. Horizontal distribution, abundance, and mortality 25.5 °C in August and the minimum was found to be 12.34 rates of anchovy (Engraulis encrasicolus) eggs °C in April. Throughout the sampling, the average surface During horizontal samplings, 438.33 ind./100 m3 eggs (a water temperature at stations A2 and C2 was calculated total of 14,535 eggs) and 8.00 ind./100 m3 larvae (a total to be 20.12 ± 4.43 °C and 20.68 ± 0.84 °C, respectively of 256) were collected between May and September. In (Figure 2). The minimum surface water salinity of station June, the maximum numbers of eggs (8430 total) were A2 was 17.24‰ in April and the maximum was 18.39‰ in encountered. In the horizontal distribution, the largest September; the minimum at station C2 was 17.11‰ in June number of eggs was found in June at station A2 (2401.43 and the maximum was 17.68‰ in September. The average ind./100 m3). Anchovy eggs were found only in stations surface water salinity at stations A2 and C2 was measured B1 and C1 in May. During June and July, anchovy eggs to be 17.81 ± 0.36‰ and 17.50 ± 0.32‰, respectively were encountered at all stations. During September, 2.06 (Figure 3). The average temperatures measured to a depth ind./100 m3 and 229.82 ind./100 m3 eggs were calculated of 50 m were respectively 15.12 ± 5.866 °C and 16.46 ± at stations A2 and C2, respectively. The most larvae in the 6.227 °C, while average salinities were 18.49 ± 1.216‰ horizontal samplings were found during August at station and 18.56 ± 1.131‰. Temperature of the surface water was B1 (37.84 ind./100 m3) (Table 1). found to be 21.18 °C in June and 23.90 °C in July. Salinity The eggs were obtained at all stations in June and was determined to be 17.68‰ in June and 17.90‰ in July.
Recommended publications
  • European Anchovy Engraulis Encrasicolus (Linnaeus, 1758) From
    European anchovy Engraulis encrasicolus (Linnaeus, 1758) from the Gulf of Annaba, east Algeria: age, growth, spawning period, condition factor and mortality Nadira Benchikh, Assia Diaf, Souad Ladaimia, Fatma Z. Bouhali, Amina Dahel, Abdallah B. Djebar Laboratory of Ecobiology of Marine and Littoral Environments, Department of Marine Science, Faculty of Science, University of Badji Mokhtar, Annaba, Algeria. Corresponding author: N. Benchikh, [email protected] Abstract. Age, growth, spawning period, condition factor and mortality were determined in the European anchovy Engraulis encrasicolus populated the Gulf of Annaba, east Algeria. The age structure of the total population is composed of 59.1% females, 33.5% males and 7.4% undetermined. The size frequency distribution method shows the existence of 4 cohorts with lengths ranging from 8.87 to 16.56 cm with a predominance of age group 3 which represents 69.73% followed by groups 4, 2 and 1 with respectively 19.73, 9.66 and 0.88%. The VONBIT software package allowed us to estimate the growth parameters: asymptotic length L∞ = 17.89 cm, growth rate K = 0.6 year-1 and t0 = -0.008. The theoretical maximum age or tmax is 4.92 years. The height-weight relationship shows that growth for the total population is a major allometry. Spawning takes place in May, with a gonado-somatic index (GSI) of 4.28% and an annual mean condition factor (K) of 0.72. The total mortality (Z), natural mortality (M) and fishing mortality (F) are 2.31, 0.56 and 1.75 year-1 respectively, with exploitation rate E = F/Z is 0.76 is higher than the optimal exploitation level of 0.5.
    [Show full text]
  • Anchovy Early Life History and Its Relation to Its Surrounding Environment in the Western Mediterranean Basin
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Digital.CSIC SCI. MAR., 60 (Supl. 2): 155-166 SCIENTIA MARINA 1996 THE EUROPEAN ANCHOVY AND ITS ENVIRONMENT, I. PALOMERA and P. RUBIÉS (eds.) Anchovy early life history and its relation to its surrounding environment in the Western Mediterranean basin ALBERTO GARCÍA1 and ISABEL PALOMERA2 1Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, Aptdo. 285. Fuengirola, 29640 Málaga, Spain. 2Institut de Ciències del Mar. CSIC, Passeig Joan de Borbó, s/n, 08039 Barcelona, Spain. SUMMARY: This paper is a review on the anchovy early life history in the western Mediterranean. There is evidence of latitudinal differences in the duration of the spawning period associated with regional temperature variations. The main spawning areas of the anchovy are located in the Gulf of Lyons and at the shelf surrounding the Ebro river delta. The exten- sions of spawning grounds seem to be linked to the size of the shelf and to the degree of hydrographic enriching-process- es. Punctual studies on egg and larval ecology have been made mainly in the areas of the main spawning grounds, report- ing preliminary results on growth, feeding, condition and mortality estimates. Biomass estimation by the Daily Egg Pro- duction Method (DEPM) has also been applied at the northern region. Key words: Anchovy, Engraulis encrasicolus, eggs and larvae, reproduction, Western Mediterranean. RESUMEN: PRIMEROS ESTADIOS DE DESARROLLO DE LA ANCHOA Y SU RELACIÓN CON EL AMBIENTE EN EL MEDITERRÁNEO OCCI- DENTAL. – Este trabajo es una revisión de los estudios realizados sobre las primeras fases de desarrollo de la anchoa del Mediterráneo occidental.
    [Show full text]
  • © Iccat, 2007
    A5 By-catch Species APPENDIX 5: BY-CATCH SPECIES A.5 By-catch species By-catch is the unintentional/incidental capture of non-target species during fishing operations. Different types of fisheries have different types and levels of by-catch, depending on the gear used, the time, area and depth fished, etc. Article IV of the Convention states: "the Commission shall be responsible for the study of the population of tuna and tuna-like fishes (the Scombriformes with the exception of Trichiuridae and Gempylidae and the genus Scomber) and such other species of fishes exploited in tuna fishing in the Convention area as are not under investigation by another international fishery organization". The following is a list of by-catch species recorded as being ever caught by any major tuna fishery in the Atlantic/Mediterranean. Note that the lists are qualitative and are not indicative of quantity or mortality. Thus, the presence of a species in the lists does not imply that it is caught in significant quantities, or that individuals that are caught necessarily die. Skates and rays Scientific names Common name Code LL GILL PS BB HARP TRAP OTHER Dasyatis centroura Roughtail stingray RDC X Dasyatis violacea Pelagic stingray PLS X X X X Manta birostris Manta ray RMB X X X Mobula hypostoma RMH X Mobula lucasana X Mobula mobular Devil ray RMM X X X X X Myliobatis aquila Common eagle ray MYL X X Pteuromylaeus bovinus Bull ray MPO X X Raja fullonica Shagreen ray RJF X Raja straeleni Spotted skate RFL X Rhinoptera spp Cownose ray X Torpedo nobiliana Torpedo
    [Show full text]
  • Updated Checklist of Marine Fishes (Chordata: Craniata) from Portugal and the Proposed Extension of the Portuguese Continental Shelf
    European Journal of Taxonomy 73: 1-73 ISSN 2118-9773 http://dx.doi.org/10.5852/ejt.2014.73 www.europeanjournaloftaxonomy.eu 2014 · Carneiro M. et al. This work is licensed under a Creative Commons Attribution 3.0 License. Monograph urn:lsid:zoobank.org:pub:9A5F217D-8E7B-448A-9CAB-2CCC9CC6F857 Updated checklist of marine fishes (Chordata: Craniata) from Portugal and the proposed extension of the Portuguese continental shelf Miguel CARNEIRO1,5, Rogélia MARTINS2,6, Monica LANDI*,3,7 & Filipe O. COSTA4,8 1,2 DIV-RP (Modelling and Management Fishery Resources Division), Instituto Português do Mar e da Atmosfera, Av. Brasilia 1449-006 Lisboa, Portugal. E-mail: [email protected], [email protected] 3,4 CBMA (Centre of Molecular and Environmental Biology), Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal. E-mail: [email protected], [email protected] * corresponding author: [email protected] 5 urn:lsid:zoobank.org:author:90A98A50-327E-4648-9DCE-75709C7A2472 6 urn:lsid:zoobank.org:author:1EB6DE00-9E91-407C-B7C4-34F31F29FD88 7 urn:lsid:zoobank.org:author:6D3AC760-77F2-4CFA-B5C7-665CB07F4CEB 8 urn:lsid:zoobank.org:author:48E53CF3-71C8-403C-BECD-10B20B3C15B4 Abstract. The study of the Portuguese marine ichthyofauna has a long historical tradition, rooted back in the 18th Century. Here we present an annotated checklist of the marine fishes from Portuguese waters, including the area encompassed by the proposed extension of the Portuguese continental shelf and the Economic Exclusive Zone (EEZ). The list is based on historical literature records and taxon occurrence data obtained from natural history collections, together with new revisions and occurrences.
    [Show full text]
  • Geographic Pattern of Sushi Product Misdescription in Italy—A Crosstalk Between Citizen Science and DNA Barcoding
    foods Article Geographic Pattern of Sushi Product Misdescription in Italy—A Crosstalk between Citizen Science and DNA Barcoding Anna Maria Pappalardo *, Alessandra Raffa, Giada Santa Calogero and Venera Ferrito Department of Biological, Geological and Environmental Sciences, Section of Animal Biology “M. La Greca”, University of Catania, Via Androne 81, 95124 Catania, Italy; [email protected] (A.R.); [email protected] (G.S.C.); [email protected] (V.F.) * Correspondence: [email protected]; Tel.: + 39-095-730-6051 Abstract: The food safety of sushi and the health of consumers are currently of high concern for food safety agencies across the world due to the globally widespread consumption of these products. The microbiological and toxicological risks derived from the consumption of raw fish and seafood have been highlighted worldwide, while the practice of species substitution in sushi products has attracted the interest of researchers more than food safety agencies. In this study, samples of sushi were processed for species authentication using the Cytochrome Oxidase I (COI) gene as a DNA barcode. The approach of Citizen Science was used to obtain the sushi samples by involving people from eighteen different Italian cities (Northern, Central and Southern Italy). The results indicate that a considerable rate of species substitution exists with a percentage of misdescription ranging from 31.8% in Northern Italy to 40% in Central Italy. The species most affected by replacement was Thunnus thynnus followed by the flying fish roe substituted by eggs of Mallotus villosus. These results Citation: Pappalardo, A.M.; indicate that a standardization of fish market names should be realized at the international level Raffa, A.; Calogero, G.S.; Ferrito, V.
    [Show full text]
  • Morphometric Variation Among Anchovy (Engraulis Encrasicholus, L.) Populations from the Bay of Biscay and Iberian Waters
    ICES CM 2004/EE:24 Morphometric variation among anchovy (Engraulis encrasicholus, L.) populations from the Bay of Biscay and Iberian waters Bruno Caneco, Alexandra Silva, Alexandre Morais Abstract For management purposes, the European Atlantic anchovy is separated in two distinct stocks, one distributed in the Bay of Biscay (ICES Sub-Area VIII) and the other occupying mainly the southern part of ICES Division IXa (Bay of Cadiz). However, spatio-temporal irregularities in the dynamics of the Sub-Area VIII stock as well as scant knowledge on the IXa anchovy biology lead ICES to recommend more studies on population dynamics and possible relationships between areas. The present work describes morphometric differences between the two stocks based on the analysis of 10 samples collected within the area from Bay of Biscay to the Bay of Cadiz during two consecutive years (2000 and 2001). Distances on a “Truss Network” were computed from 2D landmark coordinates obtained from digitized images of each individual and corrected from the effect of fish size. Principal Component Analysis was applied to the shape data, as well as a Multidimensional Scaling to the squared Mahalonobis distances (D2) between every pair of sample centroids to visualise clustering. The significance of the computed D2 distances was also statistically tested. Finally, Artificial Neural Networks were applied to assess the robustness of sample groups highlighted in the previous analyses. Results indicate a separation between samples from the Bay of Biscay and those from Division IXa, which is stable over time, as well as a north-south cline along the Portuguese and Bay of Cadiz area.
    [Show full text]
  • A Study on European Anchovy (Engraulis Encrasicolus) Swimbladder with Some Considerations on Conventionally Used Target Strength
    Turkish Journal of Zoology Turk J Zool (2019) 43: 203-214 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1809-21 A study on European anchovy (Engraulis encrasicolus) swimbladder with some considerations on conventionally used target strength Meltem OK*, Ali Cemal GÜCÜ Institute of Marine Sciences, Middle East Technical University, Erdemli, Mersin, Turkey Received: 17.09.2018 Accepted/Published Online: 31.01.2019 Final Version: 01.03.2019 Abstract: Hydroacoustic surveys are one of the prime methods to assess the commercially top-ranked small pelagic stocks. The method relies on acoustic scattering from a fish, which is largely controlled by the size and morphology of the swimbladder. In this study, the changes in the size of the European anchovy swimbladder sampled in the Black Sea were investigated. Ventral cross-sectional area (by photographing the ventrally dissected fish) and volume (by dorsal and lateral X-raying) of the swimbladders were estimated. Comparison of areas showed that the stomach fill and presence of viscera did not have a statistically significant impact on the swimbladder size while the hepatosomatic index showed significant impact. Although the vertical distribution of the anchovy is naturally not very wide due to absence of sufficient oxygen below 100 m, sampling depth showed significant impact on the volume of the swimbladder. However, it was also observed during X-ray imaging that a considerable number of fish (87%) had deflated swimbladders. The reasons for this variability, which may have significant implication on the acoustic estimations and stock assessment, were also discussed. The importance of acclimatization of the fish at surface conditions in studies addressing changes in swimbladder morphometry was underlined.
    [Show full text]
  • The Black Sea Populations of Anchovy*
    SCI. MAR., 60 (Supl. 2): 219-225 SCIENTIA MARINA 1996 THE EUROPEAN ANCHOVY AND ITS ENVIRONMENT, I. PALOMERA and P. RUBIÉS (eds.) The Black Sea populations of anchovy* ALEXANDER K. CHASHCHIN YugNIRO, Azov-Black Sea Fish Stocks Lab., 2 Sverdlova, Kerch, 334500 Crimea, Ukraine. SUMMARY: A complex method of race determination based on the genetic, parasitological and morphological traits of the population was proposed to obtain a reliable scheme of distribution and migrations of the Azov and Black Sea anchovy stocks. The abundance of anchovy was determined using the data from surveys performed with standard trawl and hydroa- coustic equipment. Experiments revealed considerable changes in the Azov anchovy’s gene pool. The main reason was the increasing of water salinity as a result of river in-flow regulation. The excessive industrial catching also promoted the process. As a result, the proportion of hybrids increased. According to the data of the acoustic surveys in the waters of the former USSR in the period from 1980 to 1988, the average biomass of the Black Sea anchovy aggregations was 309,000 tons, and the biomass of the Azov anchovy, 169,000 tons. Since 1988 the situation of these stocks have dramatically changed. A great decrease of the populations has occurred. That has in all evidence been caused by excessive captures of anchovy by the USSR and Turkey. An additional important negative factor were the intrusions of a jellyfish, Mnemiopsis leidyi. The biomass of the anchovy near the Georgian coast increased up to 165,000 tons after the Mnemiopsis outbreak had passed its peak in winter 1991-92.
    [Show full text]
  • Variation in Life-History Traits of European Anchovy Along a Latitudinal Gradient: a Bioenergetics Modelling Approach
    Vol. 617-618: 95–112, 2019 MARINE ECOLOGY PROGRESS SERIES Published May 16§ §§ https://doi.org/10.3354/meps12574 Mar Ecol Prog Ser Contribution to the Theme Section ‘Drivers of dynamics of small pelagic fish resources: OPENPEN biology, management and human factors’ ACCESSCCESS Variation in life-history traits of European anchovy along a latitudinal gradient: a bioenergetics modelling approach Martin Huret1,*, Kostas Tsiaras2, Ute Daewel3, Morten D. Skogen4, Paul Gatti1, Pierre Petitgas5, Stelios Somarakis6 1Ifremer, STH/LBH, 29280 Plouzané, France 2Hellenic Centre for Marine Research, Anavyssos, Greece 3Helmholtz Centre Geesthacht, Institute of Coastal Research, 21502 Geesthacht, Germany 4Institute of Marine Research, 5817 Bergen, Norway 5Ifremer, EMH, 44311 Nantes, France 6Hellenic Centre for Marine Research, Heraklion, Greece ABSTRACT: Anchovy Engraulis encrasicolus distribution in European waters spans from the Mediterranean Sea to the North Sea, and is expected to expand further north with global warming. Observations from the eastern Mediterranean (North Aegean Sea), the Bay of Biscay and the North Sea reveal latitudinal differences in growth, maximum size, fecundity and timing of repro- duction. We set up a mechanistic framework combining a bioenergetics model with regional physical−biogeochemical models providing temperature and zooplankton biomass to investigate the underlying mechanisms of variation in these traits. The bioenergetics model, based on the Dynamic Energy Budget theory and initially calibrated in the Bay of Biscay, was used to simulate growth and reproduction patterns. Environment partly explained the increased growth rate and larger body size towards the north. However, regional calibration of the maximum assimilation rate was necessary to obtain the best model fit. This suggests a genetic adaptation, with a pattern of cogradient variation with increasing resource towards the north, in addition to a countergradi- ent thermal adaptation.
    [Show full text]
  • General Surface Circulation Controls the Interannual Fluctuations
    www.nature.com/scientificreports OPEN General surface circulation controls the interannual fuctuations of anchovy stock biomass in the Central Mediterranean Sea Bernardo Patti1, Marco Torri1,2 & Angela Cuttitta1,3 The sustainable exploitation of small pelagic fsh populations, characterized by short life span and early age at frst reproduction, is typically more infuenced by the success of annual recruitment rather than by fshing mortality. Recruitment strength, in turn, is related to the high environmental variability characterizing the pelagic fsh habitats, able to strongly afect the survival of early stages, from hatching to recruitment. Here, we consider the case study of anchovy (Engraulis encrasicolus) stock in the Strait of Sicily (Central Mediterranean). The interannual fuctuations exhibited over an 18-year long period by this fsh population was found to be mainly linked to surface circulation patterns, as far as they are able to control retention/dispersal processes of larval stages. We frstly used Lagrangian simulations to reproduce the fate of anchovy early stages during their planktonic phase. Larval retention indices constructed from the output of the simulations were able alone to explain a large proportion of variance (up to 70%) in yearly biomass of the anchovy population, outclassing the other environmental factors considered in this study. Such results are relevant for fsheries management, for all fsh stocks characterized by potentially high vulnerability of early life stages. Te importance of environmental forcings as drivers for the interannual variability in the standing stock biomass of small pelagic fsh species has been well documented in several papers1–3. In general, this applies to r-strategist fsh species, characterized by short life span, early age at frst reproduction, high number of ofspring and low ofspring survival rates, which in turn can heavily afect recruitment success and stock biomass levels.
    [Show full text]
  • Sustainable Exploitation of Small Pelagic Fish Stocks Challenged by Environmental and Ecosystem Changes: a Review
    BULLETIN OF MARINE SCIENCE, 76(2): 385–462, 2005 SUSTAINABLE EXPLOITATION OF SMALL PELAGIC FISH STOCKS CHALLENGED BY ENVIRONMENTAL AND ECOSYSTEM CHANGES: A REVIEW Pierre Fréon, Philippe Cury, Lynne Shannon, and Claude Roy ABSTRACT Small pelagic fish contribute up to 50% of the total landing of marine species. They are most abundant in upwelling areas and contribute to food security. Exploit- ed stocks of these species are prone to large interannual and interdecadal variation of abundance as well as to collapse. We discuss why small pelagic fish and fisheries are so “special” with regard to their biology, ecology, and behavior. Two adjectives can sum up the characteristics of pelagic species: variability and instability. Analy- ses of the relationships between small pelagic fish and their physical environment at different time-scales illustrate the complexity of the interplay between exploita- tion and environmental impacts. How small pelagic fish species are positioned and related within the trophic web suggests that these species play a central role in the functioning and dynamics of upwelling ecosystems. Finally, we discuss the sustain- able exploitation of small pelagic fisheries through appropriate management, focus- ing on the resilience to exploitation, a comparison of different management options and regulatory mechanisms. We recommend that statistical, socio-economical, and political merits of a proposed two-level (short- and long-term) management strategy be undertaken. Despite constant progress in understanding the complex processes involved in the variability of pelagic stock abundance, especially at short and medium time scales, our ability to predict abundance and catches is limited, which in turn limits our ca- pacity to properly manage the fisheries and ensure sustainable exploitation.
    [Show full text]
  • Swimbladders in Mesopelagic Fishes Bibliography
    Swimbladders in Mesopelagic Fishes Bibliography Hope Shinn, Librarian, LAC Group on assignment at NOAA Central Library NCRL subject guide 2021-06 DOI: 10.25923/a1p9-zh44 June 2021 U.S. Department of Commerce National Oceanic and Atmospheric Administration Office of Oceanic and Atmospheric Research NOAA Central Library – Silver Spring, Maryland Table of Contents Background & Scope ................................................................................................................................. 2 Sources Reviewed ..................................................................................................................................... 2 References ................................................................................................................................................ 3 1 Background & Scope This bibliography is a representative sample of relevant literature on swimbladders in mesopelagic fish and their acoustic properties. References included in this bibliography are mainly from peer-reviewed, academic literature and span the years 1954-2021. The references are listed alphabetically by first author. Sources Reviewed The following databases were used to identify sources: Clarivate Analytics’ Web of Science: Science Citation Index Expanded and Social Science Index; EconLit; ProQuest’s Science and Technology including Aquatic Science Fisheries Abstracts; Elsevier’s Science Direct; JSTOR; EBSCO’s Academic Search Complete and Environment Complete; NOAA’s Institutional Repository; the Biodiversity
    [Show full text]