| dc.description.abstract | The delineation of grouper stocks in Saleh Bay is crucial for ensuring accurate
and sustainable fisheries management. Currently, Saleh Bay exhibits high species
diversity, with 21 grouper species identified. However, over the past five years,
increased fishing activity has led to overexploitation, necessitating conservation
measures. Grouper fishing takes place both inside and outside Saleh Bay, with the
catches being landed in Sumbawa Island. While data on fishing activities inside
Saleh Bay are well documented, information regarding fishing outside the bay, such
as in Sailus Island and Medang Island, remains limited. Therefore, comprehensive
catch recording is essential for future fisheries management. Additionally, it is
important to determine whether the grouper stocks caught inside and outside Saleh
Bay belong to the same population or are distinct. If they are separate populations,
differentiated management strategies must be implemented to ensure the
sustainability of grouper resources in the region.
The objectives of this study have been addressed to assess characteristics and
general condition of grouper fisheries in Saleh Bay, West Nusa Tenggara, Indonesia
(chapter 3 and chapter 4), to delineate the stock of leopard coral grouper (P.
leopardus) using various methods (morphology, fish parasite, and molecular
genetics) between Saleh Bay and Sailus Island (chapter 5), to identify the stock of
the orange-spotted grouper (E. coioides) using DNA barcoding in Saleh Bay, West
Nusa Tenggara, Indonesia (chapter 6), and to identify stock of orange-spotted
grouper (E. coioides) using fish parasites in Saleh Bay, West Nusa Tenggara,
Indonesia (chapter 7).
This study integrates multiple approaches to better understand the population
dynamics of grouper fisheries in Saleh Bay. Stock identification is conducted
through morphological analyses (morphometric-meristic), molecular genetics, and
fish parasites. Additionally, fisheries conditions in Saleh Bay are examined using
statistical modelling, including diversity indices, fish biological parameters,
exploitation levels, and factors affecting Catch Per Unit Effort (CPUE) using
Generalized Linear Models (GLMs). The findings of this research are expected to
provide valuable insights into the status of grouper stocks and the environmental
conditions in Saleh Bay. This information can serve as the foundation for
developing sustainable fisheries management strategies for the future.
By integrating morphometric, molecular genetics, and parasitological
evidence, this study demonstrates consistent stock differentiation between Saleh
Bay and adjacent comparison waters. For Plectropomus leopardus, morphometric
discrimination indicates pronounced separation between specimens from Saleh Bay
and Sailus Island, accompanied by different growth patterns both of localities.
These findings are substantiated by genetic analyses, which reveal subpopulation
level segregation between the two localities. Parasitological patterns further support
this differentiation: endoparasite assemblages differ markedly in both composition
and abundance, and these differences correspond with variation in stomach
contents, implying spatial heterogeneity in prey resources and trophic dynamics. In
Epinephelus coioides, evidence for localized population structure is indicated by
DNA barcoding, which places Saleh Bay individuals within a distinct geographic
cluster. This signal is consistent with parasitological results showing that parasite
communities in Saleh Bay form a discrete assemblage relative to those observed in
other waters. Therefore, based on three approaches provides support for
recognizing Saleh Bay populations of P. leopardus and E. coioides as distinct stock
units. Consequently, management interventions in Saleh Bay may be most effective
when implemented under a spatially explicit framework that treats the Saleh Bay as
an independent management unit to improve sustainable grouper fisheries
management.
Future research should prioritize broader spatiotemporal sampling, high
resolution population genomics, otolith-based tracers, and refined parasite
indicators to validate stock boundaries and mechanisms of differentiation.
Integrating movement ecology, reproductive dynamics, and trophic studies will
clarify demographic connectivity and local residency. Finally, implementing stock
structure into management strategy evaluation supported by socioeconomic
assessments will enable Saleh Bay to be managed as an effective, spatially explicit
unit for long-term grouper fisheries sustainability. | |
