Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 9040
Title: Deep-sea fish assemblages (300-2100 m) in the Eastern Pacific off Northern Mexico
Author: Edgar Cruz-Acevedo, N. Tolimieri, Hugo Aguirre-Villaseñor
Publication Year: In press
Journal: Marine Ecology Progress Series

Knowledge about deep-sea (> 200 m depth) fish assemblages  along the Pacific coast of Mexico (23° N-32° N) has geographical and temporal gaps. Here, we describe the bathydemersal fish assemblages (300-2100 m) off the western coast of Baja California, México (BC) and evaluate their relationship with latitude and environmental factors (depth, temperature, dissolved oxygen (DO), latitude, salinity, organic matter (OM), organic carbon (OC) and grain size distribution of the substratum (clay, silt and sand proportions). A total of 2445 fishes were caught (18 orders, 36 families and 75 species: 27 mesopelagic, 10 bathypelagic and 38 bathydemersal; eight new records). The accumulation curves for bathydemersal species richness did not asymptote suggesting that increased sampling effort is required to estimate the true species richness. Species richness increased with DO and depth, while diversity was affected by the percentage of clay in sediment. We found four latitude-depth assemblages: South-Shallow (< 28° N, < 700 m), South-Medium (< 28° N, 700-1300 m), North-Medium (> 28° N, 700-1300 m) and North-Deep (> 28° N, 1300-2100 m). The South-Medium assemblage had both the highest diversity and species richness, while North-Deep was the least diverse stratum but had the highest evenness. The delimitation of medium depth strata was complicated due to the combined effect of latitude, depth and the Oxygen Minimum Zone (OMZ). Southern assemblages were dominated by tropical species, while northern assemblages shared species with the southern California assemblages. Apparently, the latitudinal transition starts around 28° N, at least during the summer.

Theme: Ecosystem approach to improve management of marine resources
Foci: Provide scientific support for the implementation of ecosystem-based management