Species distribution models of tropical deep-sea snappers

Deep-sea fisheries provide an important source of protein to Pacific Island countries and territories that are highly dependent on fish for food security. However, spatial management of these deep-sea habitats is hindered by insufficient data. We developed species distribution models using spatially limited presence data for the main harvested species in the Western Central Pacific Ocean. We used bathymetric and water temperature data to develop presence-only species distribution models for the commercially exploited deep-sea snappers Etelis Cuvier 1828, Pristipomoides Valenciennes 1830, and Aphareus Cuvier 1830. We evaluated the performance of four different algorithms (CTA, GLM, MARS, and MAXENT) within the BIOMOD framework to obtain an ensemble of predicted distributions. We projected these predictions across the Western Central Pacific Ocean to produce maps of potential deep-sea snapper distributions in 32 countries and territories. Depth was consistently the best predictor of presence for all species groups across all models. Bathymetric slope was consistently the poorest predictor. Temperature at depth was a good predictor of presence for GLM only. Model precision was highest for MAXENT and CTA. There were strong regional patterns in predicted distribution of suitable habitat, with the largest areas of suitable habitat (> 35% of the Exclusive Economic Zone) predicted in seven South Pacific countries and territories (Fiji, Matthew & Hunter, Nauru, New Caledonia, Tonga, Vanuatu and Wallis & Futuna). Predicted habitat also varied among species, with the proportion of predicted habitat highest for Aphareus and lowest for Etelis. Despite data paucity, the relationship between deep-sea snapper presence and their environments was sufficiently strong to predict their distribution across a large area of the Pacific Ocean. Our results therefore provide a strong baseline for designing monitoring programs that balance resource exploitation and conservation planning, and for predicting future distributions of deep-sea snappers.Céline Gomez, Ashley J. Williams, Simon J. Nicol, Camille Mellin, Kim L. Loeun, Corey J. A. Bradsha

Limited genetic structure among broad-scale regions for two commercially harvested, tropical deep-water snappers in New Caledonia

We estimated the spatial population connectivity of Etelis carbunculus and E. coruscans based on measures of population genetic structure using the mitochondrial DNA control region. We collected samples from three areas separated by a minimum of 200 km around New Caledonia. We identified two separate genetic groups for E. carbunculus and a single group for E. coruscans. There were many singleton haplotypes distributed among geographic regions, indicating minimal spatial differentiation in genetic structure between regions for each species, although one of the genetic groups for E. carbunculus was in only two of the three regions. Conservation and management directives should consider both species as a single genetic stock among these three widespread regions. Our results provide evidence that stock structure might be less variable in the South Pacific than reported elsewhere, possibly indicating that trans-boundary management may be required in this region for deep-water snapper fisheries. Further refinement (including taxonomy) is required for E. carbunculus to characterize the different lineages observed.Kim L. Loeun, Sharyn Goldstien, Dianne Gleeson, Simon J. Nicol, Corey J. A. Bradsha

Review of the life history characteristics, ecology and fisheries for deep-water tropical demersal fish in the Indo-Pacific region

© 2016, Her majesty the Queen in Right of Australia.Deep-water tropical fishes support locally significant commercial fisheries, high value recreational fisheries, and culturally and economically important artisanal and subsistence fisheries throughout the Indo-Pacific region. The main species captured by these fisheries are deep-water snappers (Lutjanidae), groupers (Epinephelidae), and emperors (Lethrinidae). Quantitative assessments of deep-water tropical fisheries have been limited by a lack of adequate biological and fisheries data. We review the biology and ecology of deep-water tropical fishes, discuss the implications for assessment and management of tropical deep-water fisheries, and provide perspectives on future research priorities. We found that biological and fisheries information is lacking for the majority of deep-water tropical fishes. Furthermore, many studies were constrained by low samples sizes and the use of methods that have not been validated or verified. Most species for which reliable information was available were reported to have extended longevities (>20 years), low rates of natural mortality (M < 0.15), and slow to modest growth rates (K = 0.12–0.25). These life history traits indicate a low production potential for many deep-water tropical fishes, and suggest that sustainable exploitation rates and potential yields may be low. There is a need for more representative and adequate studies of deep-water tropical fishes and for improved fisheries data collection and the use of consistent methods in addition to information sharing to facilitate the development of robust data-poor assessment techniques for these species