THE TEHUELCHE SCALLOP, AEQUIPECTEN TEHUELCHUS^TORQ., 1846), FROM SAN JOSÉ GULF (ARGENTINA): SPATS SETTLEMENT DURING THE COLLAPSE OF THE FISHERY

Abstract

In the last 25 years the Tehuelche scallop from the San José Gulf has supported a fishery with local importance (150-200 workers and 1 to2.5 million US$/yr). Two systematic surveys carried out in 1995 and 1996 documented the collapse ofthe stock. The fishery was closed in 1996. Beyond the explosive decline in total abundance, there was a dramatic change in the distribution profile ofthe populations. This can potentially have decompensatory effects in the stock recovery. To explore the larval availability, as a whole, 96 artificial collectors were anchored in 6 sites of the upper infralittoral of the San José Gulf during the reproductive seasons 1995/96 and 1996/97. At each site 2 ropes with 4 col lector bags each were anchored: 2 bags at 2.5 m from the bottom (lower level) and 2 at 5 m (upper level). Captation records (averages: 1995/96= 19.0 and 1996/97= 216.8 spats/col lector bag) indícate that larval availability
was negligible at the beginningoftheclosure ofthe fishery and it significantly increased one year later, suggesting an incipient recovery that should be evident in commercial sizes from 1999. Results suggest that potentially decompensatory effects due to the dramatic change in the concentration profile are probably beingneutralised by thescarcereproductiveaggregations remaining in the upper infralittoral and/orin deeperareas.The futureofthe fisherydependsonthatthe fishery administraron establishes reproductive reserves and efficient and permanentControls in a short-time to avoid illegal fishing.