Vulnerability of elasmobranchs caught as bycatch in the grouper longline fishery in the Gulf of Gabès, Tunisia

Published: Mar 30, 2023
bycatch demersal longline elasmobranchs Mediterranean Sea vulnerability

The present study aims to quantify the effect of the grouper demersal longline fishery to elasmobranchs in the Gulf of Gabès to support future conservation actions for the most vulnerable species. Data from 162 demersal longline sets carried out during the grouper fishing seasons in 2016 and 2017 were analyzed. At least 17 elasmobranch species were caught, representing about 50% of the total catch in number which exceeded the target catch of groupers Epinephelus spp. (44.15%). Elasmobranchs were present in 139 (85.80%) out of the 162 examined sets, while the frequency of occurrence per set varied greatly depending on the species. The nominal Catches Per Unit Effort of all species combined was 3.07 specimens per 1,000 hooks/hour of fishing. Sharks and batoids contributed equally to the total elasmobranch catch, comprising 51.84% and 48.16% in terms of number, respectively. Mustelus mustelus, Carcharhinus plumbeus and Squalus spp. were the most abundant species, representing 45.65% of the total elasmobranch catch, whereas the remaining shark species were rarely caught (6.19%). Batoids were dominated by Glaucostegus cemiculus, which represented 19.07% of the total elasmobranch catch in number, followed by Dasyatis spp. (8.91%), Raja clavata (7.1%) and Taeniura grabata (4.59%). The elasmobranchs discarded due to their low commercial value and/or small size represented 11.34% of the total catch in number. According to the results of the Productivity and Susceptibility Analysis, the coastal viviparous elasmobranch species in the study area are highly vulnerable to the grouper longline fishery activity and should be carefully managed to reduce the likelihood of overfishing.

Article Details
  • Section
  • Research Article
Download data is not yet available.
Abella, A., Mancusi, C., Serena, F., 2011. Sustainability of bycatch of sharks and finfish in a Norway lobster fishery. In: GFCM Workshop on Stock Assessment of Selected Species of Elasmobranchs, Brussels, 12-16 December 2011.
Alfaro-Shigueto, J., Mangel, J. C., Bernedo, F., Dutton, P.H., Seminoff, J. A. et al., 2011. Small-scale fisheries of Peru: a major sink for marine turtles in the Pacific. Journal of Applied Ecology, 48, 1432-1440.
Andrzejaczek, S., Lucas, T.C.D., Goodman, M.C., Hussey, N.E., Armstrong, A.J. et al., 2022. Diving into the vertical dimension of elasmobranch movement ecology. Science Advances, 8, eabo1754.
Barausse, A., Correale, V., Curkovic, A., Finotto, L., Riginella, E. et al., 2014. The role of fisheries and the environment in driving the decline of elasmobranchs in the northern Adriatic Sea. ICES Journal of Marine Science, 71 (7), 1593-1603.
Béjaoui, B., Ben Ismail, S., Othmani, A., Ben Abdallah-Ben Hadj Hamida, O., Chevalier, C. et al., 2019. Synthesis review of the Gulf of Gabès (eastern Mediterranean Sea, Tunisia): Morphological, climatic, physical oceanographic, biogeochemical and fisheries features. Estuarine, Coastal and Shelf Science, 219, 395-408.
Bousquet, C., Bouet, M., Patrissi, M., Cesari, F., Lanfranchi, J.B. et al., 2022. Assessment of catch composition, production and fishing effort of small-scale fisheries: The case study of Corsica Island (Mediterranean Sea). Ocean and Coastal Management, 218, 105998.
Bradai, M.N., Saidi, B., Bouaïn, A., Guélorget, O., Capapé, C., 2005. The Gulf of Gabès (Central Mediterranean): Nursery area for the sandbar shark, Carcharhinus plumbeus (Nardo, 1827) (Chondrichthyes: Cacharhinidae). Annales. Series Historia Naturalis, 15 (2), 187-194.
Bradai, M.N., Saidi, B., Enajjar, S., Bouain, A., 2006. The Gulf of Gabès: a spot for the Mediterranean elasmobranchs. p. 107-117. In: The Proceedings of the Workshop on Mediterranean Cartilaginous Fish with Emphasis on Southern and Eastern Mediterranean.
Baṣusta, N., Keskin, C., Serena, F., Seret, B. (Eds). Turkish Marine Research Foundation, Turkey. Bradai, M. N., Saidi, B., Enajjar, S., 2012. Elasmobranchs of the Mediterranean and Black Sea: Status, ecology and biology. Bibliographic analysis. Studies and Reviews, General Fisheries Commission for the Mediterranean, N°91, Italy, FAO, 103 pp.
Bradai, M.N., Saidi, B., Enajjar, S., 2018. Overview on Mediterranean Shark’s Fisheries: Impact on the Biodiversity. p. 211-230. In: Marine Ecology - Biotic and Abiotic Interactions. Muhammet Turkoglu (Ed.). IntechOpen.
Camhi, M.D., Valenti, S.V., Fordham, S.V., Fowler, S.L., Gibson, G., 2009. The conservation status of pelagic sharks and rays: Report of the IUCN Shark Specialist Group Pelagic Shark Red List Workshop. IUCN Species Survival Commission Shark Specialist Group, Newbury, UK, X + 78 pp.
Carluccio, A., Capezzuto, F., Maiorano, P., Sion, L., D’Onghia, G., 2021. Deep-Water Cartilaginous Fishes in the Central Mediterranean Sea: Comparison between Geographic Areas with Two Low Impact Tools for Sampling. Journal of Marine Science and Engineering, 9, 686.
Carpentieri, P., Nastasi, A., Sessa, M., Srour, A., (eds). 2021. Incidental catch of vulnerable species in Mediterranean and Black Sea fisheries – A review. Studies and Reviews. General Fisheries Commission for the Mediterranean, N°101. Rome, FAO. 320 pp.
Cashion, M.S., Baillya, N., Pauly, D., 2019. Official catch data underrepresent shark and ray taxa caught in Mediterranean and Black Sea fisheries. Marine Policy, 105, 1-9.
Ceyhan, T., Hepkafadar, O., Tosunoğlu, Z., 2010. Catch and size selectivity of small-scale fishing gear for the smoothhound shark Mustelus mustelus (Linnaeus, 1758) (Chondrichthyes: Triakidae) from the Aegean Turkish coast. Mediterranean Marine Science, 11, 213-223.
Clarke, T.M., Espinoza, M., Ahrens, R., Chaves R.R., Wehrtmann, I.S., 2018. Assessing the vulnerability of demersal elasmobranchs to a data-poor shrimp trawl fishery in Costa Rica, Eastern Tropical Pacific. Biological Conservation, 217, 321-328.
Colloca, F., Enea, M., Ragonese, S., Di Lorenzo, M., 2017. A century of fishery data documenting the collapse of smoothhounds (Mustelus spp.) in the Mediterranean Sea. Aquatic Conservation: Marine and Freshwater Ecosystems, 27 (6), 1145-1155.
Cope, J.M., DeVore, J., Dick, E.J., Ames, K., Budrick, J. et al., 2011. An approach to defining stock complexes for U.S. west coast groundfishes using vulnerabilities and ecological distributions. North American Journal of Fisheries Management, 31,589-604.
Cortés, E., Brooks, E.N., Shertzer, K.W., 2015. Risk Assessment of cartilaginous fish populations. ICES Journal of Marine Science, 72, 1057-1068.
Dell’Apa, A., Kimmel, D.G., Clò S., 2012. Trends of fish and elasmobranch landings in Italy: associated management implications. ICES Journal of Marine Science, 69(6), 1045- 1052.
Duffy, L., Griffiths, S., 2019. Assessing attribute redundancy in the application of productivity- susceptibility analysis to data-limited fisheries. Aquatic Living Resources, 32, 20.
Dulvy, N.K., Fowler, S.L., Musick, J.A., Cavanagh, R.D., Kyne, P.M. et al., 2014. Extinction risk and conservation of the world’s sharks and rays. eLife, 3, e00590.
Dulvy, N.K., Farrell, E.D., Buscher, E., 2016. Mustelus punctulatus. The IUCN Red List of Threatened Species 2016: e. T161485A16527861. Accessed on 19 October 2022.
Dulvy, N.K., Walls, R.H.L., Abella, A., Serena, F., Bradai, M.N., 2020. Raja miraletus (amended version of 2019 assessment). The IUCN Red List of Threatened Species 2020: e.T124569516A176535719. Accessed on 19 October 2022.
Ebert, D.A., Dando, M., 2020. Field Guide to Sharks, Rays & Chimaeras of Europe and the Mediterranean. Princeton University Press, Woodstock, 384 pp.
Echwikhi, K., Saidi, B., Bradai, M.N., Bouain, A., 2013. Preliminary data on elasmobranch gillnet fishery in the Gulf of Gabès, Tunisia. Journal of Applied Ichthyology, 29 (5), 1080-1085.
Echwikhi, K., Saidi, B., Bradai M.N., 2014. Elasmobranchs longline fisheries in the Gulf of Gabès (southern Tunisia). Journal of the Marine Biological Association of the United Kingdom, 94 (1), 203-210.
Ellis, J.R., Dulvy, N.K., Serena, F., 2016. Raja clavata. The IUCN Red List of Threatened Species 2016: e. T39399A103113598. Accessed on 19 October 2022.
Enajjar, S., Saidi, B., Bradai, M.N., 2015. The Gulf of Gabès (Central Mediterranean Sea): a nursery area for sharks and batoids (Chondrichthyes: Elasmobranchii). Cahiers de Biologie Marine, 56 (2), 143-150.
Farrell, E.D., Dulvy, N.K., 2016. Mustelus mustelus. The IUCN Red List of Threatened Species 2016: e.T39358A16527988. Accessed on 19 October 2022.
Ferrari, A., Di Crescenzo, S., Cariani, A., Crobe, V., Benvenuto, A. et al., 2021. Puzzling over spurdogs: molecular taxonomy assessment of the Squalus species in the Strait of Sicily. The European Zoological Journal, 88 (1), 181-190.
Ferretti, F., Myers, R.A., Serena, F., Lotze, H.K., 2008. Loss of large predatory sharks from the Mediterranean Sea. Conservation Biology, 22 (4), 952-964.
Ferretti, F., Osio, G.C., Jenkins, C.J., Rosenberg, A.A., Lotze, H.K., 2013. Long-term change in a meso-predator community in response to prolonged and heterogeneous human impact. Scientific Reports, 3, 1057.
Ferretti, F., Walls, R.H.L., Musick, J., Stevens, J., Baum, J.K. et al., 2016. Carcharhinus plumbeus. The IUCN Red List of Threatened Species 2016: e.T3853A16527809. Accessed on 19 October 2022.
Furlong-Estrada, E., Galván-Magaña, F., Tovar-Ávila, J., 2017. Use of the productivity and susceptibility analysis and a rapid management-risk assessment to evaluate the vulnerability of sharks caught off the west coast of Baja California Sur, Mexico. Fisheries Research, 194, 197-208.
Gallagher, A.J., Kyne, P.M., Hammerschlag, N., 2012. Ecological risk assessment and its application to elasmobranch conservation and management. Journal of Fish Biology, 80, 1727-1748.
Gülşahin, A., Soykan, O., 2017. Catch composition, lengthweight relationship and discard ratios of commercial longline fishery in the Eastern Mediterranean. Cahiers de Biologie Marine, 58, 1-7.
Hamdaoui, B., 2010. Les élasmobranches dans les débarquements des chalutiers au port de pêche de Sfax, golfe de Gabès. MSc Thesis. University of Sfax, Tunisia, 93 pp.
Hobday, A.J., Smith, A.D.M., Stobutzki, I.C., Bulman, C., Daley, R. et al., 2011. Ecological risk assessment for the effects of fishing. Fisheries Research, 108, 372-384.
Jribi, I., Echwikhi, K., Bradai, M.N., Bouain, A., 2008. Incidental capture of sea turtles by longlines in the Gulf of Gabès (South Tunisia): a comparative study between bottom and surface longlines. Scientia Marina, 72 (2), 337-342.
Jung, A., Buscher, E., 2016. Taeniurops grabatus. The IUCN Red List of Threatened Species 2016: e.T161513A90728912. Accessed on 19 October 2022.
Kinney, M.J., Simpfendorfer, C.A., 2009. Reassessing the value of nursery areas to shark conservation and management. Conservation Letters, 2, 53-60.
Kousteni, V., Kasapidis, P., Kotoulas, G., Megalofonou, P., 2016. Evidence of high genetic connectivity for the longnose spurdog Squalus blainville in the Mediterranean Sea. Mediterranean Marine Science, 17 (2), 371-383.
Kousteni, V., Mazzoleni, S., Vasileiadou, K., Rovatsos, M., 2021. Complete Mitochondrial DNA Genome of Nine Species of Sharks and Rays and Their Phylogenetic Placement among Modern Elasmobranchs. Genes, 12 (3), 324.
Lloret, J., Biton-Porsmoguer, S., Carreño, A., Di Franco, A., Sahyoun, R. et al., 2020. Recreational and small-scale fisheries may pose a threat to vulnerable species in coastal and offshore waters of the western Mediterranean. ICES Journal of Marine Science, 77 (6), 2255-2264.
Lteif, M., 2015. Biology, distribution and diversity of cartilaginous fish species along the Lebanese coast, eastern Mediterranean. PhD Thesis, Université de Perpignan Via Domitia, France, 309 pp.
Mancusi, C., Morey, G., Serena, F., 2016. Raja radula. The IUCN Red List of Threatened Species 2016: e. T161339A16527984. Accessed on 19 October 2022.
Mancusi, C., Baino, R., Fortuna, C., De Sola, L., Morey, G. et al., 2020. MEDLEM database, a data collection on large Elasmobranchs in the Mediterranean and Black seas. Mediterranean Marine Science, 21, 276-288.
Martínez-Candelas, I.A., Pérez-Jiménez, J.C., Espinoza-Tenorio, A., McClenachan, L., Méndez-Loeza, I., 2020. Use of historical data to assess changes in the vulnerability of sharks. Fisheries Research, 226, 105526.
Maynou, F., Sbrana, M., Sartor, P., Maravelias, C., Kavadas, S. et al., 2011. Estimating trends of population decline in long-lived marine species in the Mediterranean Sea based on fishers’ perceptions. PloS ONE, 6 (7), e21818.
Micheli, F. M., De Leo, G., Butner, C., Martone, R. G., Shester, G., 2014. A risk-based framework for assessing the cumulative impact of multiple fisheries. Biological Conservation, 176, 224-235.
Moore, J.E., Cox, T.M., Lewison, R.L., Read, A.J., Bjorkland, R. et al., 2010. An interview-based approach to assess marine mammal and sea turtle captures in artisanal fisheries. Biological Conservation, 143, 795-805.
NOAA, 2010. NOAA Assessment toolbox. Productivity and Susceptibility Analysis (PSA)- Version 1.4.
Notarbartolo di Sciara, G., Bradai, M.N., Morey, G., Brahim, K., Camara L. et al., 2016. Glaucostegus cemiculus. The IUCN Red List of Threatened Species 2016: e. T63132A104009894.
Nuez, I., Gazo, M., Cardona, L., 2021. A closer look at the bycatch of medium-sized and large sharks in the northern Catalan coast (north-western Mediterranean Sea): Evidence of an ongoing decline? Aquatic Conservation: Marine and Freshwater Ecosystems, 31, 2369-2380.
Osio, G.C., Orio, A., Millar, C.P., 2015. Assessing the vulnerability of Mediterranean demersal stocks and predicting exploitation status of un-assessed stocks. Fisheries Research, 171, 110-121.
Patrick, W.S., Spencer, P., Link, J., Cope, J., Field, J. et al., 2010. Using productivity and susceptibility indices to assess the vulnerability of United States fish stocks to overfishing. Fishery Bulletin, 108, 305-322.
Peckham, S.H., Maldonado-Diaz, D., Walli, A., Ruiz, G., Crowder, L.B. et al., 2007. Small-scale fisheries bycatch jeopardizes endangered Pacific loggerhead turtles. PLoS ONE, 2 (10), e1041.
Pennino, M. G., Thomé-Souza, M. J. F., Carvalho, A. R., Fontes, L. C. S., Parente, C. et al., 2016. A spatial multivariate approach to understand what controls species catch composition in small-scale fisheries. Fisheries Research, 175, 132-141.
Rincón-Sandoval, L.A., Velázquez-Abunader, I., Brulé, T., 2019. Factors affecting catchability in longline fishing of red grouper in the Southeastern Gulf of Mexico. Transactions of the American Fisheries Society, 148, 857-868.
Saadaoui, A., Saidi, B., Elglid, A., Séret B., Bradai, M.N., 2016. Taxonomic observations on stingrays of the genus Dasyatis (Chondrichthyes: Dasyatidae) in the Gulf of Gabès (Southeastern Mediterranean Sea). Zootaxa, 4173 (2), 101-113.
Saidi, B., Enajjar, S., Bradai, M.N., 2016. Elasmobranch captures in shrimps trammel net fishery off the Gulf of Gabès (Southern Tunisia, Mediterranean Sea). Journal of Applied Ichthyology, 32, 421-426.
Saidi, B., Enajjar, S., Karaa, S., Echwikhi, K., Jribi, I. et al., 2019. Shark pelagic longline fishery in the Gulf of Gabès: Inter‐decadal inspect reveal management needs. Mediterranean Marine Sciences, 20, 532-541.
Serena, F., Ellis, J., Abella, A., Mancusi, C., Haka, F. et al., 2015. Scyliorhinus canicula. The IUCN Red List of Threatened Species 2015: e.T161307554A201955962. Accessed on 19 October 2022.
Serena, F., Mancusi, C., Morey, G., Ellis, J.R., 2016a. Dasyatis pastinaca (errata version published in 2016). The IUCN Red List of Threatened Species 2016: e.T161453A97841681. Accessed on 19 October 2022.
Serena, F., Holtzhausen, J., Ebert, D.A., Mancusi, C., 2016b. Myliobatis aquila. The IUCN Red List of Threatened Species 2016: e.T161569A16527996. Accessed on 19 October 2022.
Serena, F., Abella, A., Baino, R., Cannas, R., Carbonara, P. et al., 2018. Preliminary considerations of the status of elasmobranchs in the Italian waters. In Forum on Fisheries Science in the Mediterranean and Black Sea. Poster REF.FF2018_ TS1-2_ SERENA. Book of abstract. Rome, 338 pp.
Serena, F., Abella, A.J., Bargnesi, F., Barone, M., Colloca, F. et al., 2020. Species diversity, taxonomy and distribution of Chondrichthyes in the Mediterranean and Black Sea. The European Zoological Journal, 87 (1), 497‑536.
Soldo, A., Bariche, M., 2016. Heptranchias perlo. The IUCN Red List of Threatened Species 2016: e.T41823A16527717. Accessed on 19 October 2022.
Soldo, A., Bradai, M.N., Walls, R.H.L., 2016a. Carcharodon carcharias. The IUCN Red List of Threatened Species 2016: e.T3855A16527829. Accessed on 19 October 2022.
Soldo, A., Bradai, M.N., Buscher, E., Ebert, D.A., Serena, F., et al., 2016b. Squalus blainville. The IUCN Red List of Threatened Species 2016: e.T169229923A200982471. Accessed on 19 October 2022.
Speed, C.W., Field, I.C., Meekan, M.G., Bradshaw, C.J., 2010. Complexities of coastal shark movements and their implications for management. Marine Ecology Progress Series, 408, 275-293.
Stergiou, K.I., Moutopoulos, D.K., Erzini, K., 2002. Gillnet and longlines fisheries in Cyclades waters (Aegean Sea): species composition and gear competition. Fisheries Research, 57, 25-37.
Stevens, J.D., Bonfil, R., Dulvy, N.K., Walker, P.A., 2000. The effects of fishing on sharks, rays, and chimaeras (Chondrichthyans), and the implications for marine ecosystems. ICES Journal of Marine Science, 57, 476-494.
Tiralongo, F., Messina, G., Lombardo, B.M., 2018. Discards of elasmobranchs in a trammel net fishery targeting cuttlefish, Sepia officinalis Linnaeus, 1758, along the coast of Sicily (central Mediterranean Sea). Regional Studies in Marine Science, 20, 60-63.
Tsikliras, A., C., Stergiou, K.I., 2014. Size at maturity of Mediterranean marine fishes. Reviews in Fish Biology and Fisheries, 24, 219-268. Tsikliras, A, C., Stergiou, K, I., 2015. Age at maturity of Mediterranean marine fishes. Mediterranean Marine Science, 16 (1), 5-20.
Ungaro, N., Marano, G., De Zio, V., Pastorelli, A. M., Rositani, L., 2005. Some information on offshore bottom longline fishery in the southern Adriatic Sea (GSA 18). p. 98-102. In Report of the AdriaMed Technical Consultation on Adriatic Sea Small-Scale Fisheries. AdriaMed Technical Documents, N°15, Split, Croatia, 184 pp.
Walls, R.H.L., Buscher, E., 2016. Aetomylaeus bovinus. The IUCN Red List of Threatened Species 2016: e. T60127A81163810. Accessed on 19 October 2022.
Walls, R.H.L., Vacchi, M., Notarbartolo di Sciara, G., Serena, F., Dulvy, N.K., 2016. Gymnura altavela. The IUCN Red List of Threatened Species 2016: e.T63153A16527909. Accessed on 19 October 2022.
Worm, B., Davis, B., Kettemer, L., Ward-Paige, C.A., Chapman, D. et al., 2013. Global catches, exploitation rates, and rebuilding options for sharks. Marine Policy, 40, 194-204.
Most read articles by the same author(s)