Small-scale fisheries play a critical role in food security and contribute to nearly half of reported global fish catches. However, the status of most small-scale fisheries stocks is still poor. In data-limited situations, length-based methods have been widely applied to estimate reference points and to understand stock status. This study applied three different length-based assessment methods (length-based indicators—LBI, length-based spawning potential ratio—LBSPR, and the length-based Bayesian biomass approach—LBB) to predict fisheries stock sustainability in the Azores. Overall, the three methods showed robustness for 15 out of 18 stocks assessed and agreed on their exploitation status. The results showed that 45% of the Azorean stocks were classified assustainable stocks, 33% possiblerebuilding/overfishedand 22%overfishing/overfishedstock status. Sensitivity analysis showed that biases on the source of initial life-history parameters, especially the asymptotic length (L∞) and the ratio of natural mortality and growth coefficient (M/k), have a stronger influence on the reference points of conservation of mature individuals (LBI), spawning potential ratio and fishing mortality (LBSPR) and the biomass relative to the maximum sustainable yield (LBB). Furthermore, sensitivity analysis indicated that, among the three methods, LBI is more robust. Our findings provide some management recommendations such as (1) catches and effort should be reduced; (2) minimum landing size should be increased; (3) minimum hook size should be increased, to be applied mainly for those stocks classified as possiblerebuilding/overfishedandoverfishing/overfishedstock status.Graphical abstract

The velvet belly lantern shark (Etmopterus spinax) forms a large component of the by-catch of the longline fishery off the Azores, but is discarded due to the lack of commercial value. The distribution and some biological aspects of Etmopterus spinax were investigated from longline surveys between 1995 and 2005 off the Azores. The highest catch rates were at depths between 500 and 650m (range 250–1200 m). The overall sex ratio was 1:2.26 (M:F), with the predominance of females in all depth strata. The total length range was 17.5–48.0 cm for females and 18.5–45.0 cm for males. This species is sexually dimorphic, with females growing to a larger size than males and attaining greater size at first maturity. During the sampled months all the maturity stages were observed. The immature females predominated but the increase proportion of expecting and post-natal females between April and July could indicate a breeding season. The variations of hepatosomatic index indicate that this species maintains a fine balance between the deposition of lipids by the liver and maturity development to increase the reproductive potential.