Acoustic telemetry was used to record diel movement and habitat utilization of the salema (Sarpa salpa) (Teleostei: Sparidae) during three consecutive summers from 2000 to 2002 in the Calvi and Achiarina bays of Corsica in the Mediterranean Sea. A total of 18 fish was equipped with acoustic transmitters inserted in the body cavity, 13 were tracked in the Bay of Calvi (275 mm G 26.9 L F ), and 5 in Achiarina Bay (260 mm G 33.6 L F ). Two different systems were used to track the fish. The one used in the Bay of Calvi was a manual receiver and a directional hydrophone. The second system, used in Achiarina Bay, was a radioacoustic-positioning (RAP) system that continuously monitored the movements of the fish. Fish positions were put in a geographic information system (GIS) with information on the substratum and depth. Two patterns of behaviour could be identified in the three years. Either the fish had clearly defined daytime as opposed to night-time areas of residency, characterized by different depths and substrata or the fish persistently occupied the same sites during both day and night. In the Bay of Calvi, six fish were released 1 km from the capture site. All of them showed homing ability and returned to the site within 48 h.

In the Mediterranean Sea, the fish Sarpa salpa (Sparidae) is the only vertebrate grazer of Posidonia oceanica meadows. In order to gain knowledge about the behaviour of S. salpa and a better understanding of the meadow's primary production recycling, an original study was designed using ultrasonic telemetry to investigate activity patterns and space utilisation in the field. During June-September 2000, we compared diel movements of six adult S. salpa (249-317 mm FL and 313-633 g) in the Bay of Calvi. These fish were tagged by intraperitoneal insertion of ultrasonic transmitters. Their positions were recorded with a directional hydrophone from a small boat with an accuracy between 10 and 50 m, depending on the local environment. The tracking duration ranged from 3 to 22 days (average 11.8 ± 7.3). Locations were performed from at least dawn to dusk or early night, and one fish was tracked during the entire 24-h cycle. Fish were more mobile during the twilight periods, but statistical analysis indicated individual differences for the precise period of mobility. Two major behavioural patterns were observed: first, the fish remained in close vicinity of the harbour during the day and moved away to the north or the south at dusk to access nocturnal sites, occupying a home range of about 4.3 ha. The second behavioural pattern involved persistent occupation of the same sites during day and night within a relatively restricted home range (about 0.8 ha). Great variation in mobility was found and the same individual fish could show both kinds of behaviour. © 2002 Ifremer/CNRS/Inra/IRD/Cemagref/Éditions scientifiques et médicales Elsevier SAS. All rights reserved. RésuméRythmes d'activité de Sarpa salpa (Sparidés) dans un herbier de Posidonia oceanica : étude par télémétrie acoustique en mer Méditerranée, Corse. En Méditerranée, la saupe (S. salpa) est le seul poisson brouteur de l'herbier à P. oceanica. Améliorer nos connaissances sur le comportement de S. salpa permet une meilleure compréhension du recyclage de la production primaire de l'herbier. De juin à septembre 2000, 6 saupes (249-317 mm FL et 313-633 g) capturées dans la baie de Calvi, proche du port de Stareso ont été équipées d'un émetteur à ultrason par une insertion péritonéale et leurs positions ont été enregistrées avec un hydrophone directionnel à bord d'un bateau, avec une précision de 10 à 50 m, en fonction de l'environnement local. Les poissons ont été suivis de 3 à 22 j (moyenne 11,8 ± 7,3 j) et ont été localisés en continu depuis l'aube jusqu'au crépuscule ou au début de la nuit. Un individu a été localisé sur un cycle complet de 24 h. Les individus suivis semblent en général plus mobiles durant l'aube et le crépuscule, même si des différences individuelles ont été observées. Deux principaux types de comportements ont été constatés : (1) la saupe reste à proximité du port durant le jour et se déplace ensuite au crépuscule vers le Nord ou le Sud et occupe des espaces vitaux qui peuvent s'étendre jusqu'à 4,3 ha, (2) le comportement correspond à un...

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Two transmitter masses (2 and 6% of the fish's mass) were selected to examine the interference of tags with the behaviour of Sarpa salpa using a computerized video tracking system based on digital imaging techniques. The study demonstrated that light transmitters had no effect on the behavioural variables studied, and a substantial bias in behaviour is introduced if heavier (6%) tags are used. # 2005 The Fisheries Society of the British Isles

Elucidating factors that influence natural resources and diversity can assist managing species and their ecological functions. Key management options include protecting unique locations or implementing restrictions that more broadly protect ecological attributes and their services. To evaluate these 2 options, we examined 23 fish families in 152 unique sites in the Western and Northern Madagascar Ecoregion to test for spatial aggregation, environmental, habitat, and human influences on the fish communities. We found that there were 10 distinct communities of fish and that they were widely distributed in the region. Biomass and diversity were closely associated with the community types and showed weak spatial aggregation and environmental and market influences. Further, fishable biomass was only weakly positively associated with habitat characteristics of depth and soft coral cover and negatively associated with erect algae (R 2 = 0.06). Biomass was the strongest predictor of number of species whereas associations with light and hard coral cover were weak and median sea surface temperature (SST) and water depth had the weakest influences (all variable R 2 = 0.41). Given the weak spatial aggregation, environmental influences, high spatial and species variability, we suggest that there are few conservation priority locations. Consequently, for ecological representation and function there is a need for broad-scale spatial management that captures this heterogeneity and maintains reef fish biomass. The status of reefs in this ecoregion was fair with ~65% of the study sites having biomass > 600 kg ha −1 .