Midwater squid respond to overhead illumination by turning on numerous downward-directed photophores; they turn off the photophores when overhead illumination is eliminated. The squid are invisible when the intensity of the photophores matches the intensity of the overhead illumination. These results strongly support the theory of ventral bioluminescent countershading.

non-commercial fish species of shrimp trawls were studied monthly from october 2005 to september 2006 in mahshahr creeks (darvish, doragh, bihad, ghazaleh, ghanam, zangi and patil). the trawl nets had a cod-end mesh size of 24mm. total catch was 6431 individuals weighing 55.5kg, and included 14 species of non-commercial fish species belonging to 14 families. the caught shrimp species were from ...

The majority of squid families (Teuthoidea: Cephalopoda) exchange sodium for ammonium, creating a low-density fluid that imparts lift for neutral buoyancy. However, previous methods for measuring ammonium did not distinguish between NH4 + and various other amine compounds. The present study, using single column ion chromatography, reassessed the cation concentrations in several midwater cephalo...

Mesopelagic fish populations are characterised by high species richness and abundance, have been identified as important contributors to the active carbon fluxes in open ocean. We report variability communities of mesopelagic between five zones around Iberian Peninsula, i.e. Balears Alboran Mediterranean, Cadiz, Lisboa Galicia Atlantic. Day night samples were collected from 7 layers water colum...

Densities of nekton were estimated by comparing catch rates of two previously uncompared gear types, a beam trawl and a seine net, by day and night in a shallow seagrass (Zostera capricorni) habitat in Moreton Bay, Queensland, Australia. A total of 39,676 fish and crustaceans representing 42 species was caught. The catch rates of nekton were 1.4–68.1 times higher at night than in the day for 8 ...

Vanderhorstia mertensi Klausewitz, 1974, is a recently acknowledged alien fish in the Mediterranean Sea, hitherto observed only from Fethiye Bay, Turkey. To explore its distribution, trawl bycatch from eastern Antalya and Iskenderun was examined and an underwater survey was performed off Kas (western Antalya). An established population was found off Güvercin Island, Kas, and six specimens were ...

Objective The West Coast Groundfish Observer Program (WCGOP) collects at-sea data from limited trawl and fixed gear fleet as well as from open access nearshore, prawn, and shrimp fleets. This information is vital for determining the amount of discard and total catch of groundfish species in this region. This report summarizes discard data collected by the West Coast Groundfish Observer Program ...

Bottom trawl fishing has widespread impacts on benthic habitats and communities. The benthic response to trawling seems to be smaller or absent in areas exposed to high natural disturbance, leading to the hypothesis that natural and trawl disturbance affect benthic communities in a similar way. However, systematic tests of this hypothesis at large spatial scales and with data from sites spannin...