Identifying juvenile and sub-adult movements to inform recovery strategies for a high value fishery—European bass (Dicentrarchus labrax)

Abstract

The European bass (Dicentrarchus labrax) support high value commercial and recreational fisheries, however the Spawning Stock Biomass (SSB) of the northern Atlantic stock (ICES divisions 4.b–c, 7.a, and 7.d–h) has rapidly declined to an unsustainable level. The decline in SSB has been attributed to high fishing pressure combined with poor recruitment. By tracking juvenile fish their spatial ecology can be identified, and appropriate fisheries management policies designed to boost recruitment can be implemented. Using acoustic telemetry 146 sub-adult European bass (25.2–60 cm fork length) were tracked for up to 370 d across three sites in the southwest of the UK. Tagged fish were detected 2 724 548 times (Range: 166–106 393 detections per fish). Linear modelling estimated tagged fish were resident within 2.4–20.1 km of the site where they were first caught for 42.9–75.5% of the year. Some fish were however resident throughout summer and winter. Individual fish were also tracked moving up to 317 km to other coastal sites, 81% of which returned to their original capture site. Fisheries management should account for the high site fidelity displayed by juveniles and sub-adults of this species and coastal nursery sites should be considered essential habitat.

A novel method for identifying coded tags recorded on aquatic acoustic monitoring systems

“…Although this paper focusses on methods for tag detection rather than behaviour, animal welfare, consideration of the possible effect of tagging and external factors such as boat noise are important in interpretation of data of this nature. Both the tagging projects were home office licenced (licence numbers PD6C17B56, P81730EA5) and followed best practice for tag implantation (Bolland et al, 2019, Stamp et al, 2021. Detections in this paper were months or years after initial tagging and acute effects of tagging are unlikely.…”

“…The 'Unlocking the Severn' team tagged Twaite shad (Alosa fallax) and 58 of the 91 tagged fish were known to have left the Severn and entered the Bristol Channel in 2018 and 2019 respectively (Davies et al, 2020). The University of Plymouth University (Stamp et al, 2021) tagged 49 European sea bass (Dicentrarchus labrax) in the Taw-Torridge estuary and 51 in the River Dart on the South Coast of England. There is also the possibility that tags from long distance migrants from studies further afield may also be present.…”

Not so much a sea bass: Divergent European sea bass (Dicentrarchus labrax L.) freshwater incursions

“…The species is considered euryhaline and is a marine migrant that spawns at sea and uses transitional habitats like coastal lagoons and estuaries as nursery and feeding grounds (e.g., Elliott et al, 2007; L'Honoré et al, 2019; Pawson et al, 2007). The coexistence of sea bass residents and seasonal migrants has been described using tagging methodologies in different areas throughout the species distribution (Pontual et al, 2019; Stamp et al, 2021). In fact, juveniles, sub‐adults, and sexually mature sea bass display short‐range movements within the area of initial capture and long‐range movements to offshore areas in the winter in the English Channel (25–312 km; Stamp et al, 2021) and in the Iroise Sea (8–600 km; Pontual et al, 2019).…”

“…The coexistence of sea bass residents and seasonal migrants has been described using tagging methodologies in different areas throughout the species distribution (Pontual et al, 2019; Stamp et al, 2021). In fact, juveniles, sub‐adults, and sexually mature sea bass display short‐range movements within the area of initial capture and long‐range movements to offshore areas in the winter in the English Channel (25–312 km; Stamp et al, 2021) and in the Iroise Sea (8–600 km; Pontual et al, 2019). However, the partial migration is not confirmed for the species, with uncertainties remaining regarding the presence of distinct migratory behavior in areas such as the Bay of Biscay and the Iberian coast (Pontual et al, 2019).…”

European seabass show variable responses in their group swimming features after tag implantation

“…The wild adult chinook (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch) were among the first fish species used in such studies (Trefethen, 1956). Since then, acoustic transmitters have been incorporated in studies of a wide range of marine species (Brownscombe et al, 2019;Klinard and Matley, 2020) such as sharks (Espinoza et al, 2021), the salmonid smolt (Huusko et al, 2016), the Atlantic cod (Gadus morhua; Meager et al, 2009), the European seabass (Dicentrarchus labrax; Anras et al, 1997;Stamp et al, 2021), and the gilthead seabream (Sparus aurata; Arechavala-Lopez et al, 2012;Arechavala-Lopez et al, 2021). In addition, studies have benefited from the use of acoustic transmitters (Meager et al, 2009;Brownscombe et al, 2019;Muñoz et al, 2020); for example, studies on fish locomotion (Espinoza et al, 2021), the estimation of energetic costs (Wright et al, 2014;Zupa et al, 2015;Zupa et al, 2021;Alfonso et al, 2021a;Alfonso et al, 2022), residency patterns and habitat usage (Espinoza et al, 2020;Zhang et al, 2020;Lippi et al, 2022;Marques et al, 2022), intra-species/inter-species interactions (Barkley et al, 2020;Lees et al, 2020), feeding behavior (Føre et al, 2011), ecophysiology, and reproductive behavior (Klinard and Matley, 2020).…”