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Efectos de las Redes Agalleras sobre Aves Marinas en un Sitio Biológicamente Importante en el Noroeste del Atlántico
Author(s) -
DAVOREN GAIL K.
Publication year - 2007
Publication title -
conservation biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.2
H-Index - 222
eISSN - 1523-1739
pISSN - 0888-8892
DOI - 10.1111/j.1523-1739.2007.00694.x
Subject(s) - capelin , gadus , bycatch , fishery , forage fish , uria aalge , fishing , predation , hotspot (geology) , apex predator , geography , biology , groundfish , population , ecology , fisheries management , seabird , demography , geophysics , sociology , fish <actinopterygii> , geology
Marine biological hotspots, or areas where high abundances of species overlap in space and time, are ecologically important areas because energy flow through marine food webs, a key ecosystem process, is maximized in these areas. I investigated whether top predators aggregated at persistent spawning sites of a key forage fish species, capelin (Mallotus villosus), on the NE coast of Newfoundland during July and August 2000–2003. By examining the distributional patterns of top predators through ship‐based surveys at multiple spatial and temporal scales, I found that the biomasses of birds—dominated by Common Murres (Uria aalge) —and mammals—dominated by whale species—were concentrated along the coast, with a biological hotspot forming near two persistent spawning sites of capelin in all years. The formation of this hotspot was well defined in space and time from middle of July to middle of August, likely coinciding with the spawning chronology of capelin. Within this hotspot, there was a high spatial and temporal overlap of Common Murres and gill nets set to capture Atlantic cod (Gadus morhua). This resulted in breeding murres becoming entangled in gill nets while feeding on spawning capelin. Despite an acknowledged uncertainty of bycatch mortality, estimates for the larger regional‐scale area (1936–4973 murres/year; 0.2–0.6% of the breeding population) underestimated mortality relative to estimates within the hotspot (3053–14054 murres/year; 0.4–1.7%). Although fishing effort for Atlantic cod has declined substantially since the groundfish moratorium in 1992, chronic, unnatural, and additive mortality through bycatch continues in coastal Newfoundland. Restricted use of gill nets within this and other biological hotspots during the capelin spawning period appears to be a straightforward application of the “ecological and biologically significant area” management framework in Canada's Oceans Act. This protection would minimize murre bycatch and maintain ecosystem integrity.