Demographics and Yield–Per–Recruit Assessment of the Vulnerable Spiny Lobster Palinurus elephas in the Azores—Implications for Conservation and Fisheries Management

Abstract

The spiny lobster Palinurus elephas has been intensively harvested across its range and is generally considered overfished, with global landings declining sharply from an average of 820 t in 1960–79 to 385 t in 2000–19. Despite its economic and ecological importance, limited information is available to perform stock assessments and make robust management decisions. In this study, demographics and exploitation levels of P. elephas were determined from coastal areas of the Azores, and the relevance of these data for conservation planning was discussed. Carapace length varied between 39.6 and 174.3 mm, with mean sizes decreasing by depth. Males reached larger sizes and grew faster than females but were less dominant. Lifespan was 43 years for females and 60 years for males. The estimated mean length at first capture was 101.65 mm—around 58% of its asymptotic length. Fishing mortality and exploitation levels were close to the optimal values, indicating an uncertain future for Azorean populations if stock assessment and management initiatives are not focused on this species. Conservation and management strategies may benefit from these results under the ‘precautionary approach’ principle. However, up–to–date and accurate catch and fishing effort data need to be urgently collected.

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

“…Given the species' high first sale price and moderate mobility, P. elephas has been intensively exploited throughout its range and is today widely considered overfished (Groeneveld et al, 2013). In the Azores, the lobster fishery is still classified as a developing fishery, but recent studies have indicated a worrying situation if stock assessment and management initiatives are not developed (Santos et al, 2022a). It is therefore critical for scientists to provide policymakers with the best available information since effective management is more likely when decision-makers are properly informed.…”

“…LPUE and CPUE were estimated for P. phycis , C. conger , S. latus , S. colias , S. cretense , S. atricauda , L. forbesii , P. pagrus , S. scrofa , P. kuhlii , T. picturatus , Seriola spp., P. elephas , B. splendens , B. decadactylus and A. carbo as kg landing −1 vessel −1 and kg day at sea −1 vessel −1 , respectively. To reduce the influence of potential drivers ( e.g ., targeted species, vessel size, fishing gear) on these catch rates, generalized linear models (GLMs) were utilized to calculate standardized abundance indices (Santos et al ., 2022b). The explanatory factors included in the analysis differed across the different datasets and are reported in Table 1.…”

“…As a contribution to the assessment of the state of the priority fish and shellfish stocks exploited in the Azores, catch per unit effort (CPUE) and landing per unit effort (LPUE) of the Azorean commercial fleet were analysed in this study to produce standardized abundance indices for 16 of 22 priority stocks. Abundance indices for P. bogaraveo , R. clavata , blackbelly rosefish Helicolenus dactylopterus (Delaroche, 1809), common mora Mora moro (Risso, 1810) and silver scabbardfish Lepidopus caudatus (Euphrasen, 1788) were not investigated in this study as they have already been estimated and discussed in prior scientific literature (ICES, 2020c; Mariño‐Briceño et al ., 2022; Santos et al ., 2022b). The rough limpet Patella aspera Röding, 1798, on the other hand, was excluded as no catch data were available.…”

“…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.…”

The Use of Reproductive Indicators for Conservation Purposes: The Case Study of Palinurus elephas in Two Fully Protected Areas and Their Surrounding Zones (Central-Western Mediterranean)

“…In the European market, it can be sold for prices ranging between EUR 40 and EUR 120 per kg [ 28 ]. However, as a general trend, in the second half of the 20th century, P. elephas populations faced a severe decline of its biomass at sea [ 15 , 29 ], due to the excessive fishing that had depleted its populations [ 29 ]. For this reason, the species is assessed as “vulnerable” by the International Union for Conservation of Nature [ 30 ].…”