Can we consider the stocks of alfonsinos Beryx splendens and Beryx decadactylus from the Azores a discrete fishery management unit?

Abstract

This paper summarises the detailed information on catch, fork length, weight, sex and maturity of alfonsinos Beryx splendens and Beryx decadactylus collected from targeted surveys in Azores waters, complemented by fishery data, over the past c. 20 years. To date, it was not possible to define if the Azorean component of the population can be considered as a discrete local management unit. The reason for this is the lack of available information for these resources covering the entire spatial distribution of the species in the North Atlantic Ocean. Additionally, there are some conflicts between the different genetic results available, poor understanding about the species movements and data from the Azores show some discrepancies in aspects of reproduction. Consequently, there is no analytical assessment for this resource and the stock of Beryx spp. is currently managed based on the precautionary approach. Outputs of recent analyses are presented in this study and possible assumptions and strategies for the assessment are discussed.

Long-term changes in the diversity, abundance and size composition of deep sea demersal teleosts from the Azores assessed through surveys and commercial landings

“…The alfonsinos B. splendens and B. decadactylus normally live close to rocky bottoms between 200 and 1240 m depth (Maul, 1981(Maul, , 1986, with variation in the length-frequency distribution as a function of depth. Juveniles grow in demersal and shallower zones than areas typically inhabited by adults, but this reproductive strategy has been confirmed only for the splendid alfonsino B. splendens (see Santos et al, 2019). For the alfonsino B. decadactylus, a bigger-deeper trend was also reported, but its life cycle characteristics remain unknown because studies considering an entire population have not been developed until now.…”

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 .…”

“…However, to improve efficiency and success, managers need to define the fishery management units (FMUs) they are going to work with. The proposed FMUs should include the biological processes of the species (i.e., much of the life cycle should occur within the FMU), which are needed to link the biological self-reproduction of the resources with management actions [16,18].…”

The sustainable use and exploitation of fishes

“…around Ascension, Saint Helena, Tristan da Cunha and the Falkland Islands in the South Atlantic, and the Azores, Canary Islands and Madeira further north in the Atlantic (Couce et al ., ; Santos et al ., ), but also from the Pacific (Chang et al ., ), and the Baltic (Sendek & Bogdanov, ). This Special Issue includes papers on what sustainable exploitation means for elasmobranchs (Silva & Ellis, ) and on deep‐sea or bathypelagic fisheries (Santos et al ., ; Vieira et al ., ); one question here is, can deep‐sea fisheries ever be considered sustainable, given the longevity and particular life‐history traits of the species targeted (Vieira et al ., )? The Special Issue includes contributions where the study period covers time‐spans ranging from a few months, to several thousands of years (Barrett, ); and covering a single species, to entire fish communities (Thorpe, ).…”

“…Commercial fisheries comprised our fourth and largest theme session, and our keynote speaker emphasised that 20% of world fisheries production is now covered by sustainability certification under the Marine Stewardship Council (MSC) ecolabelling scheme (Agnew, 2019). These fisheries range from huge stocks such as Alaska pollock (Couce et al, 2019;Santos et al, 2019), but also from the Pacific (Chang et al, 2019), and the Baltic (Sendek & Bogdanov, 2019). This Special Issue includes papers on what sustainable exploitation means for elasmobranchs (Silva & Ellis, 2019) and on deep-sea or bathypelagic fisheries (Santos et al, 2019;Vieira et al, 2019); one question here is, can deep-sea fisheries ever be considered sustainable, given the longevity and particular life-history traits of the species targeted (Vieira et al, 2019)?…”