Population structure of the European conger Conger conger from the mid‐North Atlantic Ocean inferred from bathymetric distribution, length composition and movement patterns analyses

Abstract

Information about the population structure of Conger conger (L.) is scarce, being a limiting factor for fisheries assessment. To make available important baseline information and to test the hypothesis that the population in the mid‐North Atlantic (Azores region) represents a fishery management unit, fishery‐dependent and survey data relating to bathymetric distribution, length composition and movement patterns were examined. Fishing impacts were also evaluated using abundance and size trends over the last 25 years. The greatest abundance was in depths between 300 and 600 m. Sizes ranged from 14 to 260 cm, with larger individuals around seamounts. Tagging data showed a strong sedentary behaviour. Results combined with previous genetic and otolith studies indicated the stock in the Azores may represent a self‐contained population. Abundance and size trends were stable, but the species is considered vulnerable to overfishing due to its biological characteristics. Monitoring and adequate rational resource management are of utmost importance.

Trends in abundance indices derived from commercial fisheries for priority marine stocks in the Azores

“…This intensive exploitation was further reflected in the decreasing trends in abundance indices of commercially important species such as P. phycis , C. conger , S. cretense , S. scrofa , P. kuhlii , P. elephas , B. splendens and B. decadactylus . This is a worrying signal, as these species share the common characteristic of being relatively slow‐growing, long‐lived and low natural mortality species, which makes them particularly vulnerable to overfishing if there is a failure in their fisheries management actions (Medeiros‐Leal et al ., 2021; Santos et al ., 2019a, 2022a, 2022b). P. elephas is a good example of this.…”

“…To prevent and mitigate the fishing impact on the living marine resources, fishery-dependent (e.g., catch, effort, discard) and surveyderived data have been systematically collected in the Azores for the main commercial species since the 1990s (Santos et al, 2020b). In recent years, efforts have been made to analyse these data and enhance the quality of input information for the assessment of certain stocks identified as priority in the Azores under SDG Indicator 14.4.1 'Proportion of fish stocks within biologically sustainable levels' (Medeiros-Leal et al, 2021;Santos et al, 2020aSantos et al, , 2021aSantos et al, , 2021bSantos et al, , 2022aSantos et al, , 2022b.…”

Contributions to Management Strategies in the NE Atlantic Regarding the Life History and Population Structure of a Key Deep-Sea Fish (Mora Moro)

“…In this sense, additional contributions have been provided through empirical estimations of relevant biological and fishery parameters, such as length at first maturity (L m ), length at maximum possible yield (L opt ), life span (t max ), and theoretical age at length zero (t 0 ), using the estimated growth parameters (L ∞ and k; Table 2) [65,66]. Like other deep-water species [18,53,[67][68][69][70], M. moro can be considered vulnerable to overfishing because of its large size, slow growth, low natural mortality (Table 2), long life span, and late maturity (Table S1). However, besides the observed low E and F (Table 2), the empirical equations suggested an apparently healthy fished population in the Azores, with the length at which 100% of individuals are vulnerable to capture (L c ; Table 2) above the L m and L opt (Table S1), and the mean L F in the catch (Figure 5) above the L c , L m , and L opt .…”

Biological Knowledge of Thornback Ray (Raja clavata) from the Azores: Improving Scientific Information for the Effectiveness of Species-Specific Management Measures

“…In this regard, estimations of additional biological and fishery parameters, such as length at first maturity (L m ), length at maximum possible yield (L opt ), life span (t max ), and theoretical age at length zero (t 0 ), were performed by using the estimated growth parameters (L ∞ and k) as input of some empirical equations (Table S3) [118,119]. As well as other deep-water species [18,92,95,[120][121][122][123], R. clavata was characterized by the k-selected life history strategy with large size, slow growth, low natural mortality (Table 2), long life span, and late maturity (Table S1). The empirical equations also suggested a healthy fished population in the Azores, with the L c (Table S3) above the L m and L opt (Table S1), and the mean L T in the catch (Figure 5) above the L c , L m , and L opt .…”