Mesopelagic fish abundance and particle size spectrum analysis from Maria S. Merian cruise MSM26, spring 2013

One of the goals of EU BASIN is to understand variability in production across the Atlantic and the impact of this variability on higher trophic levels. One aspect of these investigations is to examine the biomes defined by Longhurst (2007). These biomes are largely based on productivity measured with remote sensing. During MSM 26, mesopelagic fish and size-spectrum data were collected to test the biome classifications of the north Atlantic. In most marine systems, the size-spectrum is a decay function with more, smaller organisms and fewer larger organisms. The intercept of the size-spectrum has been linked to overall productivity while the slope represents the "rate of decay" of this productivity (Zhou 2006, doi:10.1093/plankt/fbi119). A Laser In-Situ Scattering Transmissometer was used to collect size-spectrum data and net collections were made to capture mesopelagic fish. The relationship among the mesopelagic fish size and abundance distributions will be compared to the estimates of production from the size-spectrum data to evaluate the biomes of the stations occupied during MSM 26.

Spatially explicit estimates of stock size, structure and biomass of North Atlantic albacore tuna (Thunnus alalunga) in the North Atlantic for the period 1956-2010, compiled from the International Commission for the Conservation of Atlantic Tunas

The development of the ecosystem approach and models for the management of ocean marine resources requires easy access to standard validated datasets of historical catch data for the main exploited species. They are used to measure the impact of biomass removal by fisheries and to evaluate the models skills, while the use of standard dataset facilitates models inter-comparison. North Atlantic albacore tuna is exploited all year round by longline and in summer and autumn by surface fisheries and fishery statistics compiled by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Catch and effort with geographical coordinates at monthly spatial resolution of 1° or 5° squares were extracted for this species with a careful definition of fisheries and data screening. In total, thirteen fisheries were defined for the period 1956-2010, with fishing gears longline, troll, mid-water trawl and bait fishing. However, the spatialized catch effort data available in ICCAT database represent a fraction of the entire total catch. Length frequencies of catch were also extracted according to the definition of fisheries above for the period 1956-2010 with a quarterly temporal resolution and spatial resolutions varying from 1°x 1° to 10°x 20°. The resolution used to measure the fish also varies with size-bins of 1, 2 or 5 cm (Fork Length). The screening of data allowed detecting inconsistencies with a relatively large number of samples larger than 150 cm while all studies on the growth of albacore suggest that fish rarely grow up over 130 cm. Therefore, a threshold value of 130 cm has been arbitrarily fixed and all length frequency data above this value removed from the original data set.

Stomach content records for pelagic fish (herring, mackerel, blue whiting, albacore and bluefin tuna) in the northeast Atlantic

Fish stomach content records extracted from the DAPSTOM 4.5 database (held at the UK Centre for Environment, Fisheries and Aquaculture Science - CEFAS). Data collated as part of the EU Euro-Basin project and specifically concerning herring (Clupea harengus), mackerel (Scomber scombrus), blue whiting (Micromesistius poutassou), albacore (Thunnus alalunga) and bluefin tuna (Thunnus thynnus). The data set consist of 20720 records - collected throughout the northeast Atlantic, between 1906 and 2011 - mostly during routine fisheries monitoring research cruises.