Journal Article

An estimate of horse mackerel biomass in the North Sea, 1991–1997

Chris Rückert, Jens Floeter and Axel Temming

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 59, issue 1, pages 120-130
Published in print January 2002 | ISSN: 1054-3139
Published online January 2002 | e-ISSN: 1095-9289 | DOI:
An estimate of horse mackerel biomass in the North Sea, 1991–1997

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The biomass of horse mackerel (Trachurus trachurus) in the North Sea was estimated for the period 1991–1997. Calculation was based on a ratio estimate that related catch per unit effort (cpue) data from scientific surveys of horse mackerel to the cpue data of a reference species from the same surveys. It was assumed that both horse mackerel and the reference species were equally available to the survey gear. For the reference species, estimates of absolute biomass per age-class were available from North Sea Multispecies Virtual Population Analysis (MSVPA). That biomass was used to scale the cpue ratios and to obtain estimates of absolute biomass for horse mackerel. The method used was size-structured and spatially explicit. The inherent precision of the methodology, the choice of reference species and the effects of different spatial and body size resolutions were investigated. The final results were achieved by applying 1 cm size-classes and whiting (Merlangius merlangus) as the reference species. The spatio-temporal distribution of horse mackerel biomass was visualized using a Geographic Information System (GIS). Horse mackerel in the North Sea are split into two distinct components. The estimated biomass of the northern component is underestimated by the method described because the surveys do not cover the full extent of the stock. The biomass of the southern component in the third quarter of the year was estimated as 63 000, 163 000, 213 000, 248 000, 124 000, 147 000 and 57 000 t for the years 1991–1997 respectively.

Keywords: biomass; horse mackerel; International Bottom Trawl Survey; migration; North Sea; ratio estimate

Journal Article.  0 words. 

Subjects: Environmental Science ; Marine and Estuarine Biology

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