Canary 2019-updating highlights

Small pelagic fishery in the Canary Islands is carried out by an interannual quite variable artisanal fleet of purse-seiners. Total landings produced by the Canary purse-seiners have experienced a decrease from 2017–2019. However, it is not the case for the Atlantic chub mackerel, which not only is the main of the four species targeted by this fleet (>50%), but whose landings have increased since 2014, with European sardine and sardinellas almost absent in 2019. Concerning the length frequencies present in landings, the most relevant observation is that a noticeable increase in the modal lengths has been registered since the beginning of the monitoring programme in 2013, from around 22 cm to individuals ≥27 cm in 2019. Regarding ongoing studies, a new work has been launched based on the otolith shape analysis of a sizable sample comprising 792 otoliths corresponding to a time period from August 2016 to December 2017. A DIvisive ANAlysis (DIANA) Clustering method using the 4th wavelet obtained from otolith contours resulted in the detection of five different morphotypes or otolith phenotypes. Differences were found mainly in the collicum-antirostrum and the dorsal margin areas of the otolith contours. Two of the morphotypes represents 85% of the samples analysed, whose individuals were slightly larger than the other morphotypes, considering mean lengths (≥25 cm vs ≤24.5 cm). These very preliminary results open many future questions to be explored: 1. Do these results suggest intraspecific variation in the growth rate among phenotypes? 2. Do phenotypes proportions change in relation to seasonal variations? 3. May exist different ecological strategies related to each phenotypes? and 4. Are these otolith phenotypes present in other geographical areas?

Biología de recursos vivos de Canarias

PACA-BIO

Peer reviewed