SCRS/2004/160 Col. Vol. Sci. Pap. ICCAT, 58(4): 1348-1359 (2005)

A SERIES OF CATCH RECORDS BY THE HARPOON FISHERY IN THE STRAIT OF MESSINA FROM 1976 TO 2003

A. Di Natale1, A. Celona, A. Mangano1

SUMMARY

The harpoon fishery in the Strait of Messina, carried out since historical times, is potentially able to provide useful information about catch trends of target species, but original data are very difficult to find. Following the engagement to recover any available data, a first series of detailed catch data from 1976 to 2003 has been analysed. A total of 10 different species have been recorded. Trends in catches and CPUE (both in kg and in number), in total and for the most relevant species, show a general decreasing trend over that period, except for the Mediterranean spearfish and for the total catch in number. The trends in mean weight for the total catch and the three most relevant species are also decreasing. The fishing area, that originally included the southern Tyrrhenian Sea and the Strait of Messina, is now restricted to the latter and this might affect the trends, as well as the reduced fishing season in the last eight years (May-August, instead of April-September).

RÉSUMÉ

La pêcherie au harpon, qui est active dans le Détroit de Messine depuis des temps historiques, est potentiellement capable de fournir des informations utiles sur les tendances de capture des espèces-cibles, mais les données originales sont très difficiles à trouver. Suivant l’engagement de récupérer toute donnée disponible, une première série de données de capture détaillées, de 1976 à 2003, a été analysée. Un total de 10 espèces différentes a été enregistré. Les tendances des captures et de la CPUE (en kg en en nombre), dans leur totalité et pour les espèces plus pertinentes, indiquent une baisse générale sur cette période, exception faite du voilier méditerranéen et pour la capture totale numérique. Les tendances du poids moyen pour la prise totale et les trois espèces les plus pertinentes sont également à la baisse. La zone de pêche, qui incluait à l’origine le Sud de la mer Tyrrhénienne et le Détroit de Messine, est désormais limitée à ce dernier et ceci pourrait affecter les tendances, ainsi que la saison de pêche restreinte au cours de ces huit dernières années (mai-août, au lieu d’avril-septembre).

RESUMEN

La pesquería con arpón del Estrecho de Mesina, que se ha desarrollado desde tiempos históricos, es potencialmente capaz de proporcionar información útil sobre las tendencias de captura de las especies objetivo, pero los datos originales son muy difíciles de encontrar. Tras el compromiso de recuperar cualquier dato disponible, se ha analizado una primera serie de datos detallados de captura desde 1976 a 2003. Se registró un total de 10 especies diferentes. Las capturas y la CPUE (en kg y en número), totales y para las especies más importantes, exhiben una tendencia decreciente general en dicho periodo, con la excepción del marlín del Mediterráneo y de la captura total en número. Las tendencias en el peso medio para la captura total y para las tres especies más importantes también fueron decrecientes. La zona de pesca, que originariamente incluía el mar Tirreno meridional y el Estrecho de Mesina, se restringe actualmente a este último, y esto puede afectar a las tendencias, así como la temporada de pesca que se ha acortado en los ochos últimos años (mayo-agosto en vez de abril-septiembre).

KEYWORDS

Catch/effort; Gear selectivity; Time series analysis; Behaviour; Spawning migrations, Harpoon fishery; Catch composition; Data collection; Fishing effort; Logbooks; Large pelagic species

1 Aquastudio Research Institute, Via Trapani 6, 98121 Messina, Italy. 1348 1. Introduction

The harpoon fishery in the Strait of Messina is one of the most ancient fishing techniques to catch large pelagic fishes in the Mediterranean Sea. As reported by Oppianus (XVII century B.C.) and Plinius (1st century B.C.), the harpoon fishery was typical of the Strait of Messina, even if it become more organised around the XVI century. The fleet reached a maximum of 310 vessels at the end of the XIX century. Catch data have been collected by the local Chamber of Commerce till the XIX century (Sisci 1984, Anon. 1985), but almost all the old data have been destroyed during the terrible earthquake in 1908. As a consequence, the possibility to recover reliable long historical series is very low. In 1957, the engines were introduced in the fishing fleet, rapidly increasing the fishing effort of each vessel, but causing a relevant decreasing in the fishing fleet that reached a total of about 24 vessels in 1990 to the actual 12 vessels only.

In the past, there were watching vessels, anchored in coastal areas in various fishing grounds (each year, there was a lottery at the local harbour offices, to attribute the first day anchoring place to each vessel, called “posta”; then, every fishing day, there was a predefined rotation to the nearest fishing ground; nowadays, this sort of agreement is applied only in July). A small fleet of fast hunting vessels, with harpooners, surrounded each watching vessel, having a wooden mast with an observer. After the adoption of the engine, the fishing practice had changed.

Nowadays, there are single vessels, having a length between 11,5 to about 16 m, equipped by powerful inboard engines from 150 to 440 Hp. The shape of these vessels, called “passerelle” or “felucca” is quite unusual, because they have a high mast, from 15 to about 35 m high, with the steering place on the top. The watcher, a very experienced fisherman, is also the steersman, and his important duty is to explore the sea, recognize the possible prey and drive the vessel to allow the harpooner to do his job. All the information is passed directly by voice. A long horizontal front mast (from 20 up to a maximum of 55 m) allows the harpooner to operate over the possible prey, by launching the harpoon quite close to the fish.

Data from this fishery are very difficult to collect, because all the fishes are sold on the local market and are often landed just after each catch, because no one vessel is equipped by a refrigerator and the fishing area is often not far from the coast. Di Natale et al. (1986) provided a preliminary assessment of the catches obtained by the local fleet, based in the area of the Strait, at that time in Messina, Ganzirri and Torre Faro (Sicily), and Villa San Giovanni, Favazzina, Scilla, Bagnara Calabra and Pizzo (Calabria). Further data on catches (based on observer programmes) or on this fishery have been reported by Sisci (1984), Di Natale et al. (1988; 1995; 1998: 2000), Cavallaro and Lo Duca (1996), Di Natale (1999; 2004) and Romeo et al. (2001; 2003).

All the records provided to the local Authorities by the fishermen are seriously suspected to be not reliable, because they are based on formal statistic declaration without any controlling system, while, on the opposite, the personal and private logbook of each boat owner is very accurate, reliable, and with a lot of useful details. These logbooks are kept by each single boat owner in his private home and are considered as one of the most secret and strictly confidential paper they have.

According to the need to begin a data mining activity for the most fished species, many times requested by ICCAT, this paper reports the data from one of this private logbook, very kindly provided by one fisherman2 from Ganzirri (a fishing village north of Messina), having detailed records from 1976 to 2003, the entire activity of his vessel.

2. Methods

The data have been recovered by a very detailed logbook, containing daily records of the fishing activity of one vessel, since the first day of its fishing life (19 May 1976) till the last day of the 2003 fishing season (26 August 2003).

The logbook contains precise and detailed information about the weather conditions, the precise area where the fishery has been carried out, and the weight of each single specimen caught, with the name of the species. Additional information about specific events (maintenance, problems, etc) is also included.

2 Due to the confidential information, that might be different from the official statistical declaration done by the fishermen, here we thank Mr. Ciano (the nickname of this fisherman) for his very kind act in providing his personal logbook for scientific uses. 1349 The original data have been transformed into Excel files, with all the detailed information for any possible future analysis, than data have been grouped per catch category (total catch, main target species, other minor species), by month and year, taking into account all the fishing days (days of fishing activity, including all the days with no catches or those with a part-time activity, but excluding the days when the boat never went out of the harbour.

Then, the fishing effort unit taken into consideration is the amount of effective fishing days, following the same system proposed by Di Natale et al. (1987).

As a matter of fact, the methodology proposed by Romeo et al. (2003), which takes into consideration the effective watching time spend at sea by each vessel is applicable only when scientific observers are on board. Otherwise, this information is not reported on the fishermen’s logbooks, because they consider the day at sea as the basic unit. In the reality, even the watching time per day, which preliminary appears much more precise, includes other variables which are not included, like the temporary bad visibility conditions, the temporary effect on the sea surface of the thermal wind, the frequent glaze in various period of the day, the real number of watching fishermen, the time spent to land the catches when they happens close to the village, etc.

Due to all these factors (quite difficult to define) and to the fact that the yield is always related to each single fishing day, we propose again the effective fishing days at sea as the basic unit to calculate the fishing effort, even knowing the possible biases due to the variation in fishing time per day by season or the use of the defined and rotating fishing areas (“poste”) in July.

Other possible effort factors, like the engine power, area not applicable to this fishery, because of their small influence on the effective fishing capacity.

According to the type of data recorded by the fisherman, it is not possible to have a size frequency of the catches in length, while the precise information about each single weight allows us to calculate the average weight per year, a factor providing good information over long time series.

Weight data are related to the whole fish for all the species, while only bluefin tunas are landed and weighted gilled and gutted.

According to the high selectivity of this fishing activity, where the harpooner makes a precise choice of the prey, all the catches have been considered as target species. But, as a matter of fact, some of them are traditionally the main targets, including swordfish (Xiphias gladius), Bluefin tuna (Thunnus thynnus) and Mediterranean spearfish (Belone belone).

3. Discussion

The data related to the last 28 years of catch data from a single vessel carrying on the harpoon fishery in the area of the Strait of Messina show a total of 2358 fishing days, getting 121953 kg and 2970 specimens in total, having a mean weight of 41.1 kg. Then, the average total CPUE is 51.719 kg and 1.269 in number of fish.

The total catch of the most important target species, the swordfish (Xiphias gladius) show 73613 kg related to 1541 specimens, with a mean weight of 47.8 kg; the average CPUE for this species is 31.218 kg and 0.654 specimens per day.

The total catch of bluefin tuna (Thunnus thynnus) show 26464 kg related to 172 specimens, with a mean weight of 153.9 kg; the average CPUE for this species over the whole period is 11.223 kg and 0.073 specimens per day.

The total catch of Mediterranean spearfish (Tetrapturus belone) show 16128.5 kg related to 1190 specimens, with a mean weight of 13.6 kg; the average CPUE for this species over the whole period is 6.840 kg and 0.503 specimens per day.

Table 1 shows all the catch data related to each single year from 1976 to 2003, including the CPUE both in kg and in number of specimens. All the other species are included in one single category for presentation purposes.

As a matter of fact, in addition to the three main target species, another sever species are listed in these catches. They are: dolphinfish (Coryphaena hippurus), sunfish (Mola mola), albacore (Thunnus alalunga), leerfish (Lichia amia), greater amberjack (Seriola dumerilii), blue shark (Prionace glauca) and Smooth hammerhead

1350 (Sphyrna zigaena). Catches per species are reported on Table 2, while Figure 1 shows the relative percentage (both in kg and in number) of each single species over the total catch in the period taken into account.

It is interesting to remark that the most important species for the harpoon fishery is the swordfish, both in quantity (60.4%) and in number (51.9%), followed by the bluefin tuna in quantity (21.7%,3) but not in number (only 5.8%), while the Mediterranean spearfish is less important in quantity (13.2%) but much more important in number (40.1%). The sunfish is also relevant for the quantity (3,7%), and in number (0.9%). All the other species caught by the harpoon fishery are below 1%, either in quantity or in number of specimens.

Figures 2 to 9 show the bar charts of total catches, swordfish, bluefin tuna and Mediterranean spearfish catches by year, both in kg and number of specimens.

Catch trends in kg are generally decreasing over the last 28 years (Figures 2, 4 and 6), except for the Mediterranean spearfish (Figure 8), which shows a clear increasing trend.

Catch trends in number of specimens show a partially different situation: trends are increasing for total catches and Mediterranean spearfish (Figures 3 and 9), while they are decreasing both for swordfish and bluefin tuna (Figures 6 and 7).

CPUE data are shown with bare charts in Figures 10 to 17, both in kg and in number, always referred to one day of fishing activity. CPUE trends reflect those of the catches.

The mean weight is often regarded as an indicator of the status of fish populations. In this case, it appears quite clear that all the species target by the harpoon fishery are decreasing in mean size over time as showed on Figures 18 to 21.

4. Conclusion

From the above-mentioned data it is quite clear that the harpoon fishery is able to provide reliable information over a time period of many years, but it is necessary to recover many more logbooks with the purpose to have a broader view of the fishery and a good statistics. The limits to use data provided by a single fishing vessel are very evident, even if data quality is high.

The changes of the fishing pattern in about the last ten years, when vessels limited their fishing activity only to the areas immediately close to the Strait of Messina, avoiding going for a short time period to the Aeolian Isles (southern Tyrrhenian Sea), are potentially able to affect the general overview, because of the broader fishing area was certainly more productive, particularly in terms of bluefin tuna catches. As a matter of fact, it is well known in the literature that the southern Tyrrhenian Sea and the area around the Aeolian Isles is one of the most important spawning areas for this species. In the past, many catches have been done by the tuna purse-seine fleet thanks to the watching activity of the harpoon vessels in that area.

At the same time, there are other very important fact that can help for a better reading of the data and graphs presented in this paper. Still continuing to look at the bluefin tuna fishery over the time period taken into account, it is well known that southern Mediterranean Sea had recently become another important spawning and fishing ground, increasing its relevance at the end of the ‘90s and in the years 2000-2003. This fact resulted as a partial shifting of bluefin tuna presence in the traditional areas of the Southern Tyrrhenian Sea and the Strait of Messina. The evident decreasing of all the figures from the present data sets related to bluefin tuna might be partially linked to this behavioural change.

As concerns the main target species, the swordfish, the data might be partially affected by the reduced fishing area in the second half of the period taken into account but there are some other important factors that are relevant to the harpoon fishing activity. The negative effect of the rapid increasing of the driftnet fishing activity at the beginning of the ‘90s is very evident, possibly causing the first important decreasing in swordfish yield in the harpoon fishery in the Strait of Messina. The very high catches due to the driftnet fishery at that time are considered by the harpoon fishermen as a possible factor, as well as the disturbance created at that time by the high number of nets in the proximity of the Strait, potentially able to affect the normal behaviour of a migrating

3 It is important to remark the Bluefin tuna is the only species recorded on the logbook with gilled and gutted weight, while all the others are recorded with the whole weight. 1351 specimen. Much more stable trends are shown in the last period, because of the reduced driftnet activity in the area.

Other important indicators for the swordfish status are provided by the analysis of the mean weight trend in about the same time period (1986-2002) considered for the swordfish stock assessment carried out by ICCAT in 2003. Using only the data sets from 1986 to 2003 provided by the harpoon fishery, it is possible to have two additional graphs (Figures 22 and 23), showing a reduced slope in trends. Figure 23 shows an almost flat trend, which is not so different from the other flat trends obtained by all the swordfish analysis carried out on the Mediterranean stock in recent times (Tserpes et al. 2001, 2002). This is very important to confirm the stable trend of swordfish population in the last 18 years, even if it appears less healthy than in previous times, as a result of the high fishing pressure.

The major difference between the harpoon fishery and the other fisheries examined by Tserpes et al. (2001; 2002) is the mean weigh in the swordfish catch: it is 39.8 kg in the period 1986-2003, about the double of the mean weight reported for the other fisheries, but this is due to the specificity of the harpoon fishery, active only for the central part of the year and with an almost absolute selectivity.

Other interesting data are available for the Mediterranean spearfish (Tetrapturus belone), a species neglected either by the statistics or by official research, which is continuously increasing its importance (Di Natale et al. 2002, 2004), possibly using with a certain success an ecological niche now available in the Mediterranean pelagic environment. As reported in the previous chapter and as clearly showed by the Figures 8, 9, 16 and 17, all the catch trends for this species are remarkably increasing. This is in line with the conclusions reported in a recent paper (Di Natale et al. 2004), showing similar trends also for Mediterranean spearfish catches coming from other fishing activities (gillnets and longlines).

The slightly decreasing trend in the mean weight of Mediterranean spearfish from the harpoon fishery might be explained with the increasing catches of this species in recent years and with a broader range of gear reporting catches. This possibly means an increasing of the fishing pressure on Mediterranean spearfish, even if it is not always one of the main target for gillnets and longlines.

From a general point of view, due to the still poor knowledge on this species and to the possibility that the stock might be not very consistent, it should be useful to better follow all the landings, with the purpose to have a much more detailed figure of the Mediterranean spearfish situation. The inclusion of this species in the EC Data Collection Programme might help to improve the current knowledge on Tetrapturus belone. It is also important to remark the particular attention to be given to all the billfish, strongly supported by ICCAT SCRS.

The little numbers related to the seven other species caught by the harpoon fishery based in the Strait of Messina couldn’t help to provide more useful information about them.

The relevance to carry out a data mining research for old data sets, several times reiterated by ICCAT and other scientific fora, is clearly here confirmed.

5. Bibliography

ANON. 1985. Monografia sulla pesca del Pesce Spada nel Canale di Messina. Camera di Commercio ed Arti di Messina, reprinted adding historical notes. A. Sfameni Ed., Messina: 1-28.

DI NATALE, A., 1999. La ricerca sulla pesca: I Grandi Pelagici. In. Le Ricerche sulla Pesca e sull'Acquacoltura nell'Ambito della Legge 41/82. Parte 4: Relazioni. M.P.A., Roma, 1999; Biol. Mar. Medit., 7(4): 46-58.

DI NATALE, A, (ed.), 2004. Una rete coordinata per l’acquisizione di indici di reclutamento del tonno e del pescespada nei mari italiani. – Relazione riguardante l’area del Tirreno centro-meridionale e dello Stretto di Sicilia. 6-A-19. Report to: Direzione Generale della Pesca e dell’Acquacoltura, Ministero delle Politiche Agricole e Forestali, 96 p + all.

DI NATALE, A., E. D’Orazio, G. Leonardi, A. Mangano, N. Mento, S. Prestipino Giarritta, C. Scuderi, M. Sarà, 1987. Rilevazioni delle quantità pescate e dello sforzo di pesca esercitato nei confronti di alcune specie di Scombroidei.. Report to: Ministero della Marina Mercantile, Roma: 1-212.

1352 DI NATALE, A., E. D’Orazio, G. Leonardi, A. Mangano, N. Mento, S. Prestipino Giarritta, C. Scuderi, M. Sarà, 1988. Rilevazioni delle quantità pescate e dello sforzo di pesca esercitato nei confronti di alcune specie di Scombroidei. Relazione preliminare. Atti Sem. UU.OO. Prog. Ric. Piano Pesca Acquac., CNR, Roma, (1): 301-317.

DI NATALE, A., A. Mangano, E. Navarra, M., Valastro, 1995. Osservazioni sulla pesca dei grandi Scombroidei nei bacini tirrenici e dello Stretto di Sicilia (prosecuzione). Report to: Ministry of Agricultural, Food and Forestry Resouces, Direction General for Fishery and Aquaculture, Rome, 322-329.

DI NATALE, A., A. Mangano, E. Navarra, M., Valastro, 1998. Osservazioni sulla pesca dei grandi Scombroidei nei bacini tirrenici e dello Stretto di Sicilia. In; Le Ricerche sulla Pesca e sull'Acquacoltura nell'Ambito della Legge 41/82. Parte 1. M.P.A., Roma: 189-198.

DI NATALE, A., A. Mangano, A. Asaro, M. Bascone, A. Celona, E. Navarra, M. Valastro, B. Zava, 2000. Osservazioni sulla pesca dei grandi Scombroidei nei bacini tirrenici e dello Stretto di Sicilia. Report to: Direzione Generale Pesca ed Acquacoltura, Ministero delle Politiche Agricole e Forestali, Roma: 1-250 + all.

DI NATALE, A., A. Mangano, A. Celona, E. Navarra, M. Valastro, 2002. Size frequency composition of the Mediterranean spearfish catches in the Tyrrhenian Sea and in the Strait of Messina in the period 1994-2002. ICCAT/GFCM Expert Consultation on Stock of Large Pelagic Fishes in the Mediterranean Sea, Malta: ICCAT, SCRS/02/161.

DI NATALE, A., A. Mangano, A. Asaro, M. Bascone, A. Celona, E. Navarra, M. Valastro, B. Zava, 2002. Size frequency composition of the Bluefin Tuna catches in the Tyrrhenian Sea and in the Straits of Sicily in the period 1998-2001. ICCAT/GFCM Expert Consultation, Malta, in press, SCRS/02/46, ICCAT Coll. Vol. Sci. Pap.: 28 p.

DI NATALE, A., A. Mangano, A. Celona, M. Valastro, 2004. Size frequency distribution of the Mediterranean spearfish (Tetrapturus belone, Rafinesque) catches in the Tyrrhenian Sea and the Strait of Messina in 2003. CGPM/ICCAT Expert Consultation, Malaga. ICCAT/04/079: 8 p.

OPPIANUS, 177 B.C. De alieutica. Della caccia e della pesca. 1a ed. italiana, Roma, 1756: 1-183.

PLINIUS, Caius Secundus, Ist B.C. Naturalis Historia. Berolinii, 1552: 1-450.

ROMEO, T., S. Ancora, P. Consoli, A. Ausili, M.C. Fossi, F. Andaloro, 2003. Approccio sperimentale al calcolo dello sforzo di pesca e delle catture per unità di sforzo (CPUE) della pesca al Pescespada con l’arpone. Biol. Mar. Medit., 10 (2): 891-894.

SISCI, E., 1984. La pesca al Pesce spada nello Stretto di Messina. Sfameni ed., EDAS, Messina: 1-540.

TSERPES, G., K. Stokes, C. Darby, A. Di Natale, 2001. Analysis of swordfish fisheries data series in the central and eastern Mediterranean. Final Report. EC PR 98/0034. Report to D.G. XIV (Fishery) of the European Commission. Bruxelles, 145 pp.

TSERPES, G., C. Darby, A. Di Natale, P. Peristeraki, A. Mangano, 2002. Assessment of the Mediterranean Swordfish stock based on Greek and Italian fisheries data. ICCAT/GFCM Expert Consultation, Malta, in press, ICCAT Coll. Vol. Sci. Pap: 7p.

1353 Table 1 - Catches and CPUE related to the harpoon fishery between 1976 to 2003 in the area of the Strait of Messina (Italy).

mediterranean mediterranean YEAR fishing total catch swordfish bluefin tunaspearfish other species total catch swordfish bluefin tuna spearfish days kg No. kg No. kg No. kg No. kg No. CPUE.kg CPUE.No. CPUE.kg CPUE.No. CPUE.kg CPUE.No. CPUE.kg CPUE.No.

1976 73 6216,0 83 3792,0 64 1325,0 7 39,0 2 1060 10 85,151 1,137 51,945 0,877 18,151 0,096 0,534 0,027 1977 68 5493,0 73 3354,0 60 2092,0 11 18,0 1 29 1 80,779 1,074 49,324 0,882 30,765 0,162 0,265 0,015 1978 79 9145,0 146 6674,0 105 1997,0 11 474,0 30 115,759 1,848 84,481 1,329 25,278 0,139 6,000 0,380 1979 70 5548,0 75 3392,0 52 1974,0 13 182,0 10 79,257 1,071 48,457 0,743 28,200 0,186 2,600 0,143 1980 68 5497,0 80 3557,0 65 1865,0 10 47,0 3 28 2 80,838 1,176 52,309 0,956 27,426 0,147 0,691 0,044 1981 62 5897,0 74 3188,0 51 2553,0 16 121,0 5 35 2 95,113 1,194 51,419 0,823 41,177 0,258 1,952 0,081 1982 90 5153,0 115 3566,0 62 896,0 7 645,0 42 46 4 57,256 1,278 39,622 0,689 9,956 0,078 7,167 0,467 1983 83 4745,0 113 2995,0 60 843,0 8 894,0 44 13 1 57,169 1,361 36,084 0,723 10,157 0,096 10,771 0,530 1984 80 7815,0 98 4351,0 71 3338,0 20 126,0 7 97,688 1,225 54,388 0,888 41,725 0,250 1,575 0,088 1985 86 7098,0 103 3398,0 64 3472,0 21 228,0 18 82,535 1,198 39,512 0,744 40,372 0,244 2,651 0,209 1986 87 4216,0 143 1721,0 41 1262,0 8 1135,0 91 98 3 48,460 1,644 19,782 0,471 14,506 0,092 13,046 1,046 1987 95 3968,0 82 2693,0 62 1010,0 6 145,0 11 120 3 41,768 0,863 28,347 0,653 10,632 0,063 1,526 0,116 1988 97 4039,0 122 2745,0 67 612,0 5 652,0 48 30 2 41,639 1,258 28,299 0,691 6,309 0,052 6,722 0,495 1989 95 2963,0 82 2152,0 47 275,0 2 389,0 31 147 2 31,189 0,863 22,653 0,495 2,895 0,021 4,095 0,326 1990 90 3947,5 113 2929,0 69 515,0 3 503,5 41 43,861 1,256 32,544 0,767 5,722 0,033 5,594 0,456 1991 98 3918,0 126 1971,0 52 908,0 4 1006,0 69 33 1 39,980 1,286 20,112 0,531 9,265 0,041 10,265 0,704 1992 93 1702,0 69 1082,0 27 91,0 2 529,0 40 18,301 0,742 11,634 0,290 0,978 0,022 5,688 0,430 1993 79 2983,5 146 1648,5 42 61,0 1 1274,0 103 37,766 1,848 20,867 0,532 0,772 0,013 16,127 1,304 1994 103 3850,5 133 2633,5 66 333,0 4 884,0 63 37,383 1,291 25,568 0,641 3,233 0,039 8,583 0,612 1995 101 3907,5 133 2551,5 58 286,0 4 1070,0 71 38,688 1,317 25,262 0,574 2,832 0,040 10,594 0,703 1996 93 2500,0 94 1634,0 43 272,0 2 556,0 47 38 2 26,882 1,011 17,570 0,462 2,925 0,022 5,978 0,505 1997 83 2601,0 117 1733,5 48 26,0 1 792,0 65 49,5 3 31,337 1,410 20,886 0,578 0,313 0,012 9,542 0,783 1998 80 2396,0 84 1870,5 42 21,0 1 504,5 41 29,950 1,050 23,381 0,525 0,263 0,013 6,306 0,513 1999 85 2162,0 86 1706,0 51 25,0 1 390,0 33 41 1 25,435 1,012 20,071 0,600 0,294 0,012 4,588 0,388 2000 71 1674,5 52 1087,5 34 335,0 1 200,0 14 52 3 23,585 0,732 15,317 0,479 4,718 0,014 2,817 0,197 2001 76 4698,0 168 2026,0 53 26,0 1 1349,0 106 1297 8 61,816 2,211 26,658 0,697 0,342 0,013 17,750 1,395 2002 85 3382,0 113 1595,0 42 51,0 2 754,0 60 982 9 39,788 1,329 18,765 0,494 0,600 0,024 8,871 0,706 2003 88 4437,5 147 1567,0 43 1221,5 94 1649 10 50,426 1,670 17,807 0,489 0,000 0,000 13,881 1,068

TOTAL 2358 121953,0 2970 73613,0 1541 26464,0 172 16128,5 1190 5748 67 51,719 1,260 31,218 0,654 11,223 0,073 6,840 0,505

Table 2 - Catches of minor target species by the harpoon fishery between 1976 to 2003 in the area of the Strait of Messina (Italy).

fishing total catch dolphinfish sunfish leerfish albacore amberjack blue shark hammerhead YEAR days kg No. kg No. kg No. kg No. kg No. kg No. kg No. kg No.

1976 73 6216,0 83 40,0 3 870,0 6 29,0 1 150,0 1 1977 68 5493,0 73 1978 79 9145,0 146 1979 70 5548,0 75 1980 68 5497,0 80 28,0 2 1981 62 5897,0 74 20,0 1 15,0 1 1982 90 5153,0 115 24,0 3 22,0 1 1983 83 4745,0 113 13,0 1 1984 80 7815,0 98 1985 86 7098,0 103 1986 87 4216,0 143 28,0 2 70,0 1 1987 95 3968,0 82 10,0 1 14,0 1 96,0 1 1988 97 4039,0 122 30,0 2 1989 95 2963,0 82 17,0 1 130,0 1 1990 90 3947,5 113 1991 98 3918,0 126 33,0 1 1992 93 1702,0 69 1993 79 2983,5 146 1994 103 3850,5 133 1995 101 3907,5 133 1996 93 2500,0 94 18,0 1 20,0 1 1997 83 2601,0 117 7,5 1 21,0 1 21,0 1 1998 80 2396,0 84 1999 85 2162,0 86 41,0 1 2000 71 1674,5 52 28,0 2 2001 76 4698,0 168 28,0 2 1269,0 6 24,0 1 2002 85 3382,0 113 12,0 1 970,0 8 2003 88 4437,5 147 39,0 3 1610,0 7

TOTAL 2358 121953,0 2970 325,5 25 4719,0 27 90,0 4 50,0 3 21,0 1 350,0 3 192,0 4

% 100,00 100,00 0,27 0,84 3,87 0,91 0,07 0,13 0,04 0,10 0,02 0,03 0,29 0,10 0,16 0,13

1354 70,00

60,00

50,00

40,00

30,00

SPECIES COMPOSITION IN % COMPOSITION SPECIES 20,00

10,00

0,00 12345678910 % in kg 60,36 21,70 13,23 0,27 3,87 0,07 0,04 0,02 0,29 0,16 % in No. 51,89 5,79 40,07 0,84 0,91 0,13 0,10 0,03 0,10 0,13

Figure 1 - Species composition in the data set from harpoon fishery in the Strait of Messina from 1976 to 2003. LEGENDA: SPECIES: 1 = Swordfish; 2 = Bluefin tuna; 3 = Mediterranean spearfish; 4 = Dolphinfish; 5 = Sunfish; 6 = Leerfish; 7 = Albacore; 8 = Greater amberjack; 9 = Blue shark; 10 = Smoother hammerhead.

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TOTAL CATCHES TOTAL CATCHES y = 0,8541x + 91,294 R2 = 0,0589 10000 y = -173,94x + 6672,3 160 R2 = 0,603 9000 140 8000 120 7000 6000 100 5000 80 4000 60 3000 10 40 2000 1000 20 0 0

6 8 0 2 4 6 8 0 2 4 6 8 0 2 84 992 197 197 198 198 198 198 198 199 199 199 199 199 200 200 1976 1978 1980 1982 19 1986 1988 1990 1 1994 1996 1998 2000 2002 YEAR YEAR

Figure 2 - Total catches in kg obtained by harpoon fishery in the Strait of Messina Figure 3 - Total catches in No. obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003 (Italy) between 1976 and 2003

SWORDFISH SWORDFISH

y = -1,0282x + 69,944 7000 y = -109,16x + 4211,9 120 R2 = 0,3209 R2 = 0,5779 110 6000 100 5000 90 80 4000 70 60 3000 50 40 2000 30 1000 20 10 0 0

0 0 78 88 984 000 1976 1978 1980 1982 1 1986 1988 1990 1992 1994 1996 1998 2 2002 1976 19 1980 1982 1984 1986 19 199 1992 1994 1996 1998 200 2002 YEAR YEAR

Figure 4 - Swordfish (Xiphias gladius ) catches in kg obtained by harpoon fishery in the Figure 5 - Swordfish (Xiphis gladius ) catches in No. obtained by harpoon fishery in Strait of Messina (Italy) between 1976 and 2003 the Strait of Messina (Italy) between 1976 and 2003

BLUEFIN TUNA BLUEFIN TUNA

3500 y = -1,274x + 30,61 25 y = -0,5244x + 13,712 2 3000 R = 0,5759 R2 = 0,5129 20 2500 2000 15

1500 10 1000 5 500 0 0

4 96 980 988 990 1976 1978 1 1982 198 1986 1 1990 1992 1994 19 1998 2000 2002 1976 1978 1980 1982 1984 1986 1988 1 1992 1994 1996 1998 2000 2002 YEAR YEAR

Figure 6 - Bluefin tuna (Thunnus thynnus ) catches in kg obtained by harpoon Figure 7 - Bluefin tuna (Thunnus thynnus ) catches in No. obtained by harpoon fishery fishery in the Strait of Messina (Italy) between 1976 and 2003 in the Strait of Messina (Italy) between 1976 and 2003

MEDITERRANEAN SPEARFISH MEDITERRANEAN SPEARFISH y = 2,3996x + 7,7063 y = 27,924x + 171,12 2 2 R = 0,3905 R = 0,3157 1400 120

1200 100 1000 80 800 60 600 40 400 200 20 0 0

6 0 2 4 8 0 2 4 6 8 0 2 6 8 0 2 4 6 8 2 4 6 8 0 8 7 8 8 00 197 1978 198 19 198 1986 198 199 199 199 199 199 200 2 19 197 198 198 198 19 19 1990 199 199 199 199 200 2002 YEAR YEAR

Figure 8 - Mediterranean spearfish (Tetrapturus belone ) catches in kg obtained by Figure9 - Mediterranean spearfish (Tetrapturus belone ) catches in No. obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003 harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003

1356 TOTAL CATCHES TOTAL CATCHES y = 0,0047x + 1,1951 R2 = 0,0128 120,000 y = -2,3413x + 87,513 2,000 R2 = 0,5462

90,000 1,500

60,000 1,000

10 30,000 0,500

0,000 0,000

6 2 0 0 8 0 82 88 90 96 02 82 92 02 980 986 000 976 978 98 9 988 99 9 99 00 0 197 1978 1 19 1984 1 19 19 199 1994 19 1998 2 20 1 1 1 1 1984 1986 1 1 1 1994 1996 1 2 2 YEAR YEAR

Figure 10 - Total catches CPUE in kg obtained by harpoon fishery in the Strait of Figure 11 - Total catches CPUE in No. obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003 Messina (Italy) between 1976 and 2003

SWORDFISH SWORDFISH

120,000 2,000 y = -1,6034x + 55,502 y = -0,0173x + 0,9154 2 R2 = 0,6343 R = 0,4781 90,000 1,500

60,000 1,000

30,000 0,500

0,000 0,000

6 4 4 4 2 2 92 02 76 78 86 88 94 982 000 980 996 998 197 1978 1980 1 198 1986 1988 1990 19 199 1996 1998 2 20 19 19 1 1982 198 19 19 1990 199 19 1 1 2000 200 YEAR YEAR

Figure 12 - CPUE of Swordfish (Xiphias gladius ) in kg obtained by harpoon fishery in Figure 13 - CPUE of Swordfish (Xiphis gladius ) in No. obtained by harpoon fishery the Strait of Messina (Italy) between 1976 and 2003 in the Strait of Messina (Italy) between 1976 and 2003

BLUEFIN TUNA BLUEFIN TUNA

y = -1,274x + 30,61 60,000 0,500 y = -0,0072x + 0,1818 2 R = 0,5759 2 R = 0,5552 50,000 0,400 40,000 0,300 30,000 0,200 20,000 0,100 10,000

0,000 0,000 0 0 0 90 82 84 92 02 976 978 980 982 992 994 996 976 978 98 9 9 988 99 9 996 998 00 0 1 1 1 1 1984 1986 1988 19 1 1 1 1998 2000 2002 1 1 1 1 1 1986 1 1 1 1994 1 1 2 2 YEAR YEAR

Figure 14 - CPUE of Bluefin tuna (Thunnus thynnus ) in kg obtained by harpoon Figure 15 - CPUE of Bluefin tuna (Thunnus thynnus ) in No. obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003 fishery in the Strait of Messina (Italy) between 1976 and 2003

MEDITERRANEAN SPEARFISH MEDITERRANEAN SPEARFISH

y = 0,3226x + 1,9714 2 y = 0,0281x + 0,0828 30,000 R = 0,3078 2,000 R2 = 0,3785 25,000 1,500 20,000

15,000 1,000

10,000 0,500 5,000

0,000 0,000

0 2 2 4 6 0 84 86 96 78 80 86 92 94 02 976 978 98 98 9 9 990 99 99 9 000 002 97 9 9 984 9 990 9 9 998 00 0 1 1 1 1 1 1 1988 1 1 1 1 1998 2 2 1 1 1 1982 1 1 1988 1 1 1 1996 1 2 2 YEAR YEAR

Figure 16- CPUE of Mediterranean spearfish (Tetrapturus belone ) in kg obtained by Figure17 - CPUE of Mediterranean spearfish (Tetrapturus belone ) in No. obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003 harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003

1357 TOTAL CATCHES No.= 2970

100,0 y = -2,0126x + 72,395 R2 = 0,6648 80,0

60,0

40,0

20,0

0,0

1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 YEAR

Figure 18 - Mean weight in kg of total catches obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003

SWORDFISH No.= 1541

100,0 y = -1,064x + 61,694 R2 = 0,7625 80,0

60,0

40,0

20,0

0,0

1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 YEAR

Figure19 - Mean weight in kg of Swordfish ( Xiphias gladius ) catches obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003

BLUEFIN TUNA No.= 172 y = -1,274x + 30,61 R2 = 0,5759 350,0 300,0 250,0 200,0 150,0 100,0 50,0 0,0

1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 YEAR

Figure 20 - Mean weight in kg of Bluefin tuna ( Thunnus thynnus ) catches obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003

MEDITERRANEAN SPEARFISH No.= 1190

25,0 y = -0,2505x + 18,338 R2 = 0,4533 20,0

15,0

10,0

5,0

0,0

1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 YEAR

Figure 21 - Mean weight in kg of Mediterranean spearfish ( Tetrapturus belone ) catches obtained by harpoon fishery in the Strait of Messina (Italy) between 1976 and 2003

1358 SWORDFISH SWORDFISH

y = -0,3433x + 28,668 y = -0,0026x + 0,605 R2 = 0,126 60,000 1,500 R2 = 0,016

40,000 1,000

20,000 0,500

0,000 0,000

6 976 982 986 1 1978 1980 1982 1984 198 1988 1990 1992 1994 1996 1998 2000 2002 1976 1978 1980 1 1984 1 1988 1990 1992 1994 1996 1998 2000 2002 YEAR YEAR

Figure22 - CPUE of Swordfish (Xiphias gladius ) in kg obtained by harpoon fishery Figure 23 - CPUE of Swordfish (Xiphis gladius ) in No. obtained by harpoon in the Strait of Messina (Italy) between 1986 to 2003 fishery in the Strait of Messina (Italy) between 1986 to 2003

.

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