A relative abundance survey of sandfish, Holothuria scabra on Warrior Reef was carried out in February 2010. We surveyed 127 sites during the survey, including 70 on Warrior Reef, 30 on Dungeness Reef, 7 on Zagai Island and 20 on Iama Island. The densities of sandfish from the survey were compared to previous surveys undertaken in 1995/96, 1998, 2000, 2002 and 2004. Survey densities were found to be at similar levels to 2004, and again were ~80% less than observed in 1995/96; at which time the population was considered to be overexploited. The purpose of the survey was to monitor the recovery of this population after severe depletion during the 1990's and to recommend future management strategies.

To further monitor the recovery and investigate the feasibility of experimental fishing to monitor the fishery, a small experimental fishing exercise was undertaken. Islanders from Iama and Poruma Islands, which historically fished Warrior Reef, were engaged in the exercise. This represented a significant training and community co-management opportunity. Fishing effort was controlled to a level where there was little risk to the overall population stock status (<2 tonnes), even at the 2010 estimates of low stock size. Catch and swept area data from different locations and time of day were compared with historical survey data and estimates of catch in the early 1990s, when the fishery was first exploited. This provided information on population status and dynamics.

This project aimed to gather and synthesize information and modelling tools, to assist traditional owners in identifying suitable locations, areas and stocking rates for reef gardens in Torres Strait, for valuable hand collectable species including sandfish (H. scabra), black teatfish (H. whitmaei) and trochus (T. niloticus). This is potentially an important component in developing adaptive co-management harvest strategies in Torres Strait. Data from previous surveys were used to illustrate potential reef garden sites. No new spatial data were generated during this project.

The sandfish on Warrior Reef were surveyed in October 2002 including a resurvey of sites examined in 1995/6, 1998 and 2000. This showed that the population had continued to recover, but was still seriously depleted and we are not yet able to recommend its reopening. However, the density of the breeding cohort was the strongest ever surveyed, so we might hope for a strong recruitment in 2004. We did observe a significant change in the distribution of sandfish on Warrior Reef that may be related to habitat changes in the northern section of Warrior Reef.

This current research project was based on a population surveys of sandfish on Warrior Reef in January 2004. Sandfish density actually decreased to similar levels as in 1998, when the fishery was closed. While most of the decrease occurred in the juvenile sandfish population, the adult sandfish population had also declined since the previous survey in 2002. This result was quite unexpected given the relatively strong breeding cohort evident in 2002.

The sandfish on Warrior Reef were surveyed at 50 sites from 14 to 17 January 1998. This showed that the abundance of Holothuria scabra (sandfish) on Warrior Reef in January 1998 was between 63% and 86% (95% CI, mean 77.5%) smaller than in November 1995. The H. scabra stock in November 1995 was considered as over-exploited, therefore this reduction indicates a serious depletion. Both the fishery (2+ years old) and recruiting (one year old) year-classes are depleted, the latter the result of a depleted breeding population, indicating a direct stock-recruitment relationship for H. scabra on Warrior Reef. This indicates that the fishery stock is in a downward spiral, with progressively smaller breeding populations leading to smaller and smaller recruitments. Severe management measures are required to avoid a total collapse of the stock.

The sandfish on Warrior Reef were surveyed at 167 sites from 19 to 26 January 2000 including a resurvey of sites examined in 1995/6 and 1998. The Holothuria scabra (sandfish) population on Warrior Reef is still severely depleted. It is 53% to 81% (95% CI) smaller than the 1995/96 population, which was also considered as over-exploited. There was an average increase of about 36% in abundance since the extremely low abundance recorded in January 1998, however, this estimated recovery rate had a high uncertainty. The heavily depleted nature of the population is also confirmed by estimates of standing stock which indicate that it is unlikely that there is more than 100 tonnes of 2+ year old H. scabra on Warrior Reef. This stock size estimate is very low compared to estimates of the catch in 1995 of 1200 to 1400 tonnes, and estimates of virgin biomass of over 1600 tonnes.

The reefs of east Torres Strait were surveyed in April 2002 visiting 424 sites; this produced precise density and standing stock estimates for each species in the fishery. We used this information to assess stock status and formulate Total Allowable Catch (TAC) recommendations that will allow continued fishing while reducing the risk of stock collapse. This included a recommendation for a zero take of two overexploited species, black teatfish and surf redfish. The remaining species TACs ranged from 15 t (white teatfish) to 181 t (lollyfish) with an overall TAC of 490 t (wet landed weight). These species should form the basis for sustainable fishery in the immediate future.