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Evidence for temporal changes in ray and skate populations in the Portuguese coast (1998–2003) – its implications in the ecosystem

Published online by Cambridge University Press:  17 May 2007

Ivone Figueiredo ,
Teresa Moura ,
Pedro Bordalo-Machado ,
Ana Neves ,
Cristina Rosa  and
Leonel Serrano Gordo
Ivone Figueiredo
Affiliation:
Departamento de Recursos Marinhos, IPIMAR, Av. Brasília, 1449-006 Lisboa, Portugal
Teresa Moura
Affiliation:
Departamento de Recursos Marinhos, IPIMAR, Av. Brasília, 1449-006 Lisboa, Portugal
Pedro Bordalo-Machado
Affiliation:
Departamento de Recursos Marinhos, IPIMAR, Av. Brasília, 1449-006 Lisboa, Portugal
Ana Neves
Affiliation:
Departamento de Biologia Animal and Instituto de Oceanografia, Faculdade de Ciências de Lisboa, Bloco C2, Campo Grande, 1749–016 Lisboa, Portugal
Cristina Rosa
Affiliation:
Direcção-Geral das Pescas e Aquicultura, Av. Brasília, 1499-030 Lisboa, Portugal
Leonel Serrano Gordo
Affiliation:
Departamento de Biologia Animal and Instituto de Oceanografia, Faculdade de Ciências de Lisboa, Bloco C2, Campo Grande, 1749–016 Lisboa, Portugal
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Abstract

In mainland Portugal, rays constitute an important by-catch of multi-gear shelf fisheries. However and despite their economical importance, landing information discriminated by species is scarce. The relative stability in Portuguese annual landings of rays and skates can be misinterpreted as no evidence for species declines. The present concern on the overexploitation of individual species arises from both theoretical considerations about biological and ecological traits and for historical reasons.

This work constitutes an approach for a retrospective analysis of ray landings in mainland Portugal. Data from research surveys carried along the Portuguese coast was used to infer possible changes in species composition on Portuguese landings. Clusters were determined based on data collected during surveys from species composition for three time-periods, 1989-1991, 1995-1997 and 2001-2003. The relative importance of the associate species within clusters was the input data to define discriminating rules posteriorly used to assign clusters to landings from each commercial vessel. The results show an increase of species relative importance and changes on species abundance: Raja brachyura and Raja clavata decreased, whilst Leucoraja naevus, increased. Furthermore, it was observed a decrease on the mean weight of the two first species and a relative stability in the last one. Such results reflect the importance of species life-history characteristics in particular, on the response to fishing impact.

Keywords

Chondrichthyan fishRaja spp.Associate speciesCommercial landingsSurveysCluster predictionSpecies compositionTemporal changes
Type
Research Article
Information
Aquatic Living Resources , Volume 20 , Issue 1: New developments in coastal environment research: results from the national coastal environment program , January 2007 , pp. 85 - 93
Copyright
© EDP Sciences, IFREMER, IRD, 2007

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References

Bezdek J.C., 1981, Pattern recognition with fuzzy objective function algorithms. New York, Plenum Press.
Bezdek, J., Hathaway, R., 1988, Recent convergence results for the fuzzy c-means clustering algorithms. J. Classif. 5, 237-247.
Brander K., Blom G., Borges M.F., Erzini K., Hendersen G., MacKenzie B.R., Mendes H., Santos A.M.P., Toresen R., 2003, Changes in fish distribution in the Eastern North Atlantic; are we seeing a coherent response to changing temperature? ICES Mar. Sci. Symp. 219, 261-270.
Cardador F., Sanchéz F., Pereiro F.J., Borges M.F., Caramelo A.M., Azevedo M., Silva A., Pérez N., Martins M.M, Olaso I., Pestana G., Trujillo V., Fernandez A., 1997, Groundfish surveys in the Atlantic Iberian waters (ICES divisions VIIIc and IXa): history and perspectives. ICES CM 1997/Y:8.
Cunha M.E., 2001, Physical control of biological processes in a coastal upwelling system: comparison of the effects of coastal topography, river run-off and physical oceanography in the northern and southern parts of western Portuguese coastal waters. PhD dissertation, Lisboa, Universidade de Lisboa.
Daan N., 2001, A spatial and temporal diversity index taking into account species rarity, with an application to the North Sea fish community. ICES CM 2001/T:04.
Dimitriadou E., Hornik K., Leisch F., Meyer D., Weingessel A., 2005, Misc Functions of the Department of Statistics (e1071), TU Wien. R package version 1.5-7, URL http://CRAN.R-project.org/.
Du Buit, M.H., 1976a, The ovarian cycle of the cuckoo ray, Raja naevus (Muller and Henle), in the Celtic Sea. J. Fish Biol. 8, 199-207. CrossRef
Du Buit, M.H., 1976b, Age et croissance de Raja batis et de Raja naevus en Mer Celtique.. J. Cons. Int. Explor. Mer 37, 261-265. CrossRef
Dunn, J., 1973, A fuzzy relative of the isodata process and its use in detecting compact well separated clusters. J. Cybern. 3, 32-57. CrossRef
Dulvy, N.K., Metcalfe, J.D., Glanville, J., Pawson, M.G., Reynolds, J.D., 2000, Fishery stability, local extinctions, and shifts in community structure in skates. Cons. Biol. 14, 283-293. CrossRef
Dulvy, N.K., Jennings, S., Rogers, S.I., Maxwell, D.L., 2006, Threat and decline in fishes: an indicator of marine biodiversity. Can. J. Fish Aquat. Sci. 63, 1267-1275. CrossRef
Ellis, J.R., Dulvy, N.K., Jennings, S., Parker-Humphreys, M., Rogers, S.I., 2005, Assessing the status of demersal elasmobranchs in UK waters: a review. J. Mar. Biol. Assoc. UK 85, 1025-1047. CrossRef
Figueiredo, M.J., Figueiredo, I., Machado, P.B., 2001, Deep-water penaeid shrimps (Crustacea: Decapoda) from off the Portuguese continental slope: an alternative future resource? Fish. Res. 51, 321-326.
Fisher R.A. 1936, The use of multiple measurements in taxonomic problems. Ann. Eugen. 7, 179-188.
Garofalo, G., Gristina, M., Fiorentino, F., Fulgosi, F.C., Norrito, G., Sinacori, G., 2003, Distributional pattern of rays (Pisces, Rajidae) in the Strait of Sicily in relation to fishing pressure. Hydrobiologia 503, 245-250. CrossRef
Hastie T., Tibshirani R., Buja A., 1995, Flexible discriminant and Mixture Models. In: Kay J., Titterington D. (Eds) Neural Networks and Statistics, Oxford University Press.
Hilborn R., Walters C.J., 1992, Quantitative Fisheries Stock Assessment: Choice, dynamics and uncertainity. New York, Chapman and Hall Publishers.
Holden, M.J., 1972, The growth rates of Raja brachyura, Raja clavata and Raja montagui as determined from tagging data. J. Cons. Int. Explor. Mer 34, 161-168. CrossRef
Holden, M.J., 1975, The fecundity of Raja clavata in British waters. J. Cons. Int. Explor. Mer 36, 110-118. CrossRef
Hunter, E., Berry, F. Buckley, A. A., Stewart, S., Metcalfe, J.D., 2006, Seasonal migration of thornback rays and implications for closure management. J. Appl. Ecol. 43, 710-720. CrossRef
Machado, P.B., Gordo, L.S., Figueiredo, I., 2004, Skate and ray species composition in the Portuguese continental coast from the commercial landings. Aquat. Living Resour. 17, 231-234. CrossRef
Pascoe, S., 2006, Economics, fisheries, and the marine environment. ICES J. Mar. Sci. 63, 1-3. CrossRef
Rogers, S.I., Ellis, J.R., 2000, Changes in the demersal fish assemblages of British coastal waters during the 20th century. ICES J. Mar. Sci. 57, 866-881. CrossRef
Ryland, J.S., Ajayi, T.O., 1984, Growth and population dynamics of three Raja species (batoidea) in Carmarthen Bay, British Isles. J. Cons. Int. Explor. Mer 41, 111-120. CrossRef
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 J. Mar. Sci. 57, 476-494. CrossRef
Sousa, P., Azevedo, M., Gomes, M.C., 2006, Species-richeness patterns in space, depth, and time (1989-1999) of the Portuguese fauna sampled by bottom trawl. Aquat. Living Resour. 19, 93-103. CrossRef
Walker, P.A., Heessen, H.J.L., 1996, Long-term changes in ray populations in the North Sea. ICES J. Mar. Sci. 53, 1085-1093. CrossRef
Walker P.A., Ellis J., 1998, Ecology of rays of the north-eastern Atlantic. Proc. Biol.Skates Symp., New Orleans, Princeton Press.
Walker, P.A., Hislop, J.R.G., 1998, Sensitive skates or resilient rays? Spatial and temporal shifts in ray species composition in the central and north-western North Sea between 1930 and the present day. ICES J. Mar. Sci. 55, 392-402. CrossRef