Short-term residence and movement patterns of the annular seabream Diplodus annularis in a temperate marine reserve

Abstract

The short-term movements of a small temperate fish, the annular seabream Diplodus annularis (Linnaeus 1758), were examined using standard tag-recapture and passive acoustic telemetry in Palma Bay (NW Mediterranean), a marine protected area (MPA). The study aimed to provide valuable information for assessing the recreational fishery and its results suggest that MPAs can be used to protect the adult stock of D. annularis. All the fish tagged with standard tags were recaptured near the release locations, with a maximum distance of ∼300 m. The maximum time between release and recapture was 185 d. Two different arrays of acoustic receivers were deployed, one in 2008 and another in 2009, within the MPA. Twenty adults were surgically tagged with acoustic transmitters. Fish monitored in 2008 (n = 12) were translocated from the point of capture to analyse the movement behaviour after artificial displacement. Upon release at displaced locations, 67% of the fish moved towards the original capture location using a time of return that ranged from 0.75 to 15.25 h. Fish monitored in 2009 (n = 8) were released at the point of capture. They showed high site fidelity with a maximum period of 27 d between the first time and the last time they were detected.

Introduction

The spatio-temporal behaviour of fish is important for a number of marine management and conservation issues (Pittman and McAlpine, 2003, Botsford et al., 2009). For example, fish movements and home ranges are important factors to consider in the development of marine protected areas (MPAs). The benefits of a marine reserve depend on the rate and scale of movements of species in relation to the reserve size (Kramer and Chapman, 1999, Sale et al., 2005). To provide effective protection, MPAs must be sufficiently large to enclose the appropriate habitats in order to contain the regular movements of the target species (i.e., their home range), but also allow dispersal and cross-boundary movements of early life stages to fishing grounds (i.e., adult spillover: Kramer and Chapman, 1999, Bartholomew et al., 2008). In addition, site fidelity is also related to the possibility of using fish as bioindicators, as sedentary species are more suitable for representing local exposure to human impacts (Burger and Gochfeld, 2001). Examining how individuals use space can reveal the diversity of behaviours within a species and increase our understanding of basic ecological processes.

Acoustic telemetry has been used as an alternative as well as a complementary method to conventional mark and recapture studies for studying fish movements (Voegeli et al., 2001, Parsons and Egli, 2005, Abecasis et al., 2009). For example, this technology has allowed researchers to quantify fish home ranges within MPAs (e.g., Lowe et al., 2003, Parsons and Egli, 2005), determine site fidelity (e.g., Collins et al., 2007, Abecasis and Erzini, 2008) and obtain data on homing abilities (Kaunda-Arara and Rose, 2004, Jadot et al., 2006). This technique uses an acoustic transmitter attached to an individual and the acoustic signal is received by a hydrophone. In addition, the recent development of miniature tags has allowed transmitters to be used on small fish, which has increased the size range of animals that can be tagged. From among the different systems available for acoustic telemetry, automated systems that use arrays of acoustic listening stations have become a popular research tool (Heupel et al., 2006). These passive systems can be designed to monitor various individuals’ movements simultaneously in a broad range of spatial and temporal scales in order to infer spatial (e.g., home range) and temporal (e.g., diel activity) movement patterns. Previous studies using passive acoustic telemetry in Palma Bay Marine Reserve with Serranus scriba (March et al., 2010) and Serranus cabrilla (Alós et al., in press) showed that this technology performs well in this environment and is appropriate for small fish.

The annular seabream, Diplodus annularis (Linnaeus 1758), is a littoral benthic fish, common in the bottoms covered by seagrass beds from 0 to 50 m depth (Bauchot, 1987). This small Sparid inhabits the Mediterranean and Black Sea coast, the Atlantic from the gulf of Biscay to Gibraltar, and the Madeira and Canary Islands (Bauchot, 1987). It is classified as a rudimentary hermaphrodite (Buxton and Garratt, 1990, Alós et al., 2010), with a spawning period between May and June (Alonso-Fernández et al., in press). Total lengths (TL) at 50% maturity are 9.0 cm for males and 10.0 cm for females (Matic-Skoko et al., 2007). In the Balearic Islands (NW Mediterranean), D. annularis is one of the species most frequently targeted by recreational boat and shore anglers (Morales-Nin et al., 2005), and has a minimum legal size of 12 cm. Recent studies have used D. annularis to assess the impacts of recreational fisheries (Cardona et al., 2007, Alós et al., 2008). Thus, information on the movements of D. annularis is relevant for the management of recreational fisheries.

In this study, we used both conventional external tagging and passive acoustic telemetry to examine the short-term movement patterns of a small temperate fish, the annular seabream Diplodus annularis. The specific aims of the study were: (1) to quantify the short-term movement patterns of D. annularis; (2) to determine short-term site fidelity; and (3) to describe movement behaviour after artificial displacement.