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High-relief, complex seafloor habitats (e.g., rock and coral reef) present a number of challenges for the deployment of traditional fishing gears, such as seines, gill nets, bottom trawls, and longlines. [...]

Four species of planktonic calanold copepods that co-occur in the California Current System (Euecalanus californicus Johnson, Rhincalanus nasutus Giesbrecht, Calanus pucificus californicus Brodsky, and Metridia pacifica Brodsky) were investigated for evidence of seasonal dormancy in the San Diego Trough. Indices used to differentiate actively growing from dormant animals included developmental stage structure and vertical distribution; activity of aerobic metabolic enzymes (Citrate Synthase and the Electron Transfer System complex); investment in depot lipids (wax esters and triacylglycerols); in situ grazing activity from gut fluorescence; and egg production rates in simulated in situ conditions. None of the 4 species exhibited a canonical calanoid pattern of winter dormancy - i.e., synchronous developmental arrest as copepodid stage V, descent into deep waters, reduced metabolism, and lack of winter reproduction. Instead, Calanus pacificus californicus has a biphasic life history in this region, with an actively reproducing segment of the population in surface waters overlying a deep dormant segment in winter. Eucalanus californicus is dormant as both adult females and copepodid V's, although winter females respond relatively rapidly to elevated food and temperature conditions; they begin feeding and producing eggs within 2-3 days. Rhincalanus nasutus appears to enter dormancy as adult females, although the evidence is equivocal. Metridia pacifica shows no evidence of dormancy, with sustained active feeding, diel vertical migration behavior, and elevated activity of metabolic enzymes in December as well as in June. The four species also differ markedly in water content, classes of storage lipids, and specific activity of Citrate Synthase. These results suggest that copepod dormancy traits and structural composition reflect diverse adaptations to regional environmental conditions rather than a uniform, canonical series of traits that remain invariant among taxa and fixed across a species' range. Such interspecific and regional differences in life history traits need to be incorporated in models simulating Eastern Boundary Current pelagic ecosystem dynamics.

Bottom trawl sampling is used to estimate trends in stock abundance for groundfishes worldwide, including Pacific rockfishes (Sebastes spp.). However, trawl sampling efficiency varies spatially and the distribution of groundfish populations may change among easy- and difficult-to-survey areas over time. These concerns have prompted interest in using underwater vehicles (UVs), for which catchability is likely to decrease less in rocky habitats. In this study, we use simulation modeling to evaluate the abundance trends arising from bottom trawl sampling given density-dependent habitat selection and spatially varying catchability. We first demonstrate that relative abundance indices in this case will generally be biased measures of changes in population abundance. We also propose and evaluate a sampling design that combines data from bottom trawl and UV gears. Combined sampling has greater precision than UV sampling, lower bias than bottom trawl sampling, and is robust to moderately violated assumptions regarding sampling strata or spatial catchability. We conclude by recommending future research that could test the assumptions under which combined sampling is a feasible solution to spatially varying catchability. L'echantillonnage au chalut de fond est utilise pour estimer les tendances d'abondance des stocks pour les poissons de fond a l'echelle mondiale, dontles sebastes du Pacifique (Sebastes spp.). L'efficacite de l'echantillonnage au chalut varie cependant dans l'espace et la repartition des populations de poissons de fond entre des regions faciles et difficiles a echantillonner peut varier dans le temps. Ces difficultes ont suscite un interet pour l'utilisation de vehicules sous-marins (UV), auxquels devrait etre associee une reduction moins importante de la capturabilite dans les habitats rocheux. Nous avons utilise la modelisation par simulation pour evaluer les tendances d'abondance decoulant de releves au chalut de fond etant donne une selection d'habitats dependant de la densite et une capturabilite variable dans l'espace. Nous demontrons d'abord que les indices d'abondance relative dans ce cas constituent generalement des mesures biaisees des variations de l'abondance de populations. Nous proposons et evaluons egalement une approche d'echantillonnage qui combine des donnees de chalut de fond et d'engins d'UV. L'echantillonnage combine offre une plus grande precision que l'echantillonnage par UV et un biais plus faible que l'echantillonnage au chalut de fond, en plus d'etre robuste en cas de non-respect modere des hypotheses de depart concernant les strates echantillonnees ou la variabilite spatiale de la capturabilite. Nous recommandons que soient menees des recherches visant a verifier les conditions dans lesquelles l'echantillonnage combine constitue une solution au probleme de la variabilite spatiale de la capturabilite., Introduction Information about trends in stock abundance for many groundfish species worldwide is obtained from surveys that are conducted using scientific sampling designs. Survey data are used in combination with [...]

Crustaceans in the California Current were examined for DNA variations and how their populations were related to zooplankton in the region. A single species of crustacea was collected and zooplankton biomass calculated on the basis of bioacoustic backscattering.