Michael Trianni

2015

The Humphead Wrasse (HHW), Chelinus undulatus, is found in coral reef ecosystems throughout the Indo-Pacific region. Exhibiting a moderately long life span, low natural mortality rate and protogynous hermaphroditism, it is sensitive to unrestricted fishing pressure. This has been evidenced by significant depletion of the species in the Coral Triangle Region (Malaysia, Indonesia and the Philippines) by the live reef food fish trade (Gillett 2010). Listed as endangered by the IUCN and currently under ESA review, information on CNMI HHW has been limited to non-targeted or qualitative observations, which necessitates the need for directed studies.There are two objectives to this project. The first is to define habitat preference and generate abundance estimates for juvenile HHW on Saipan. The second is to process existing otoliths and gonads obtained opportunistically from coral reef fish landings on Saipan to generate age and growth estimates and maturation status on fish entering Saipan’s commercial reef fish markets.This project begins to addresses CNMI HHW data deficiencies. Specifically, estimation of juvenile abundance and identification of juvenile habitat preference will identify critical habitat during an important life history stage. Age and growth parameter estimation and identification of maturation status of fish entering the commercial markets on Saipan will provide insight into the population currently under harvest. Comparison of juvenile habitat with harvest locations obtained from the PIFSC funded biosampling program examines correlation between habitat and fishing pressure.There are no current, directed projects pertaining to CNMI HHW. A continuing Wake Atoll project studying HHW breeding behavior and habitat was submitted for FY15. A previous study of CNMI HHW (CRMO 2010) yielded information that cannot be applied. Non-targeted UVC coral reef fish survey work undertaken by local CNMI fisheries research and management agencies (DFW) and habitat monitoring (Coastal Resources Management) provide ancillary observations.Fishery independent survey will employ an independent double observer survey method first proposed by Nichols et al. (2000) where detection probabilities are used in generating estimates of abundance. Sabeter (2010) applied this to HHW in American Samoa to estimate abundance and preferred habitats of juvenile HHW. Collected otolith and gonads sampled from commercial spear fishing landings on Saipan will be processed by the Fish Ageing Lab at James Cook University, Townsville Australia, while gonadal histological slides will be produced by a participating PIFSC contractor.Project partners include the fisheries research and management agency of the CNMI, DFW, and Micronesian Environmental Services, a local consultant contracted to PIFSC to collect data on coral reef fish landings on Saipan.

The information generated from this project will provide several positive outcomes. The abundance and distribution of juvenile HHW will be documented for the first time in the CNMI, focused on Saipan which harbors the largest lagoon environment in the Marianas as well as the largest human population and greatest fishing pressure in the CNMI. These data will provide baseline information on the density and distribution of juveniles on Saipan, which can then be correlated with known harvest locations. This will not only inform management of potential areas of particular concern, but also afford researchers a template for subsequent questions pertaining to recruitment and growth. The description of habitat by documentation of benthic structural types as well as the collection of temperature, salinity and dissolved oxygen measures will provide detailed physiochemical requirements for juvenile HHW. Subsequent identification and delineation of habitat preferences enables the designation of critical juvenile habitat for HHW on Saipan that can then be incorporated into management plans for this species, which would be especially useful in the event of an ESA listing. The use of the independent double observer method will standardize this approach for determining juvenile abundances and habitat preferences in the US Insular Areas.Age and size at maturity estimates and transition for the HHW population derived from fishery dependent data collections will provide the most direct and immediate use of parameter estimates toward management and conservation. The Department of Lands and Natural Resources (DLNR) is currently developing regulations on size limits for reef fish species sold in the CNMI, which are based on age and size at maturity parameters by species from the peer-reviewed literature. The proposed project will therefore address a critical data gap and will allow for an accurate assessment of age and size maturity for regulatory and conservation purposes.

• Commonwealth of the Northern Mariana Islands

Fishing

Closed

Completed

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