Contrasting movements and residency of two serranids in a small Macaronesian MPA

Abstract

Protection inside marine reserves and the desired ‘reserve effect’ depend directly on the home range and sedentary behaviour of fishes throughout their lives. Benthic territorial predators are typically seen as major candidates to beneficiaries, but empirical evidence of short-versus long term residency is still surprisingly rare. We studied the inter-annual patterns of site fidelity and finer scale movements in two of the most abundant benthic predators of the NE Atlantic coastal reefs, the dusky grouper (Epinephelus marginatus) and the blacktail comber (Serranus atricauda), using passive acoustic telemetry inside and around a small marine reserve in the Azores islands, central North Atlantic. Individuals of both species resided in the reserve year-round, occupying stable core activity areas within relatively small home ranges. Groupers were detected nearly every day (n=11, median=5.0years) while combers were still detected in 2/3 of the days (n=9, median=2.0years). Some dusky groupers underwent daily short-range forays during the summer, most probably related to spawning events, whereas combers appeared to foray for longer periods with no direct relation with reproductive activity. The two species also contrast in their diel pattern, strictly diurnal in the comber but crepuscular in the grouper. This study evidences that even small reserves within the size range of most coastal reserves can accommodate the multiple-scale patterns of space use of exploited benthic territorial species, and promote the recovery of their local exploited populations in the long-term via the ‘reserve effect’ and, potentially, via the ‘larval export’ effect.