Blue whiting (Micromesistius poutassou) sex ratio, size distribution and condition patterns off Portugal

Abstract

The sex ratio is an important trait of natural populations and a key parameter for assessing the reproductive potential and stock status of exploited fish populations. In fisheries research, knowledge on spatial and temporal sex ratio variation can inform on the capacity of a population to support exploitation and environmental changes. Blue whiting (Micromesistius poutassou) shows sexual growth dimorphism after maturation, with females achieving greater lengths than males. The main goal of this work was to investigate seasonal patterns in the blue whiting sex distribution, size structure and condition in three areas along the Portuguese coast (north, southwest and south), based on bottom trawl surveys performed in autumn and winter between 1998 and 2015. Smaller blue whiting (12-24 cm) were found in shallow areas down to 250-300 m while larger individuals (>24 cm) were spread deeper down to 400-500 m. Condition factor Fulton K differed significantly between seasons in all the areas (F = 11.72; p-value <0.001) and between sexes (F = 6.14; p-value <0.05). The proportion of females changed between autumn and winter (x 2 (1) = 4.38, p = 0.03) and across depths (x 2 (1) = 4.73, p = 0.03). Thus, this study revealed seasonal and depth variations in the blue whiting sex ratio along the Portuguese coast.

Growth, reproduction and their interplay in blue whiting (Micromesistius poutassou, Risso, 1827) from the NW Mediterranean

“…This becomes apparent from 25 cm TL, when females were dominant in number. The size range found was similar to that previously observed in the Mediterranean (García et al, 1981;Macpherson and Duarte, 1991;Massutí et al, 2008;Serrat et al, 2019) and smaller than that reported for the Atlantic population (Gonçalves et al, 2017;Mahe et al, 2016). The minimum fished size, 3 cm TL, indicates that the recruitment to the demersal habitat takes place at smaller size than previously reported in the western Mediterranean, between 11.5 and 14 cm (Bas, 1964;García et al, 1981;Moranta et al, 2000) and similar to that mentioned in other Mediterranean areas (Ligurian , Northern Tyrrhenian and Ionian Seas) (D'Onghia et al, 2010;Mannini and Lanteri 2015;Viva et al 2015).…”

“…Blue whiting, Micromesistius poutassou (Risso, 1827), is a pelagic gadoid widely distributed in the North Atlantic and the Mediterranean Sea, inhabiting over the shelf edge and continental slope (Bailey, 1982;Heino et al, 2008). There is large amount of information on its biology, behavior and fisheries for the Northeast Atlantic (Bailey and Heath, 2001;Bailey, 1982;Gonçalves et al, 2017;Hátún et al, 2009;Payne et al, 2012), but less is known for the species in the Mediterranean despite it has an important commercial interest, particularly in the northern part (Bas, 1963;Bas and Calderon-Aguilera, 1989;Martin et al, 2016;Orsi-Relini and Peirano 1985;Serrat et al, 2019).…”

Evaluating Summer Flounder Spatial Sex‐Segregation in a Southern New England Estuary

“…; Gonçalves et al. ), and/or spatiotemporal sex‐segregation (Swain ; Gerritsen et al. ; Loher and Hobden ; Okamura et al.…”

“…; Gonçalves et al. ; Haugen et al. ) may bias biological reference points and compromise the success of management strategies.…”

Changes of potential catches for North-East Atlantic small pelagic fisheries under climate change scenarios

“…Mackerel performs extensive annual migrations with distinct spawning, feeding, overwintering and nursery areas (Boyd et al, 2018;. Blue whiting performs seasonal and diel vertical migrations (Gonçalves et al, 2017). Herring also undergo extensive migrations between feeding and spawning grounds (Kotterba et al, 2017).…”