Rahman, Mohammad Mustafizur
(2024)
Environmental variability as tool for fisheries resource management.
In: International Antalya Scientific Research And Innovative Studies Congress, Turkey.
Abstract
Environments play a significant role in shaping different aspects of animals' lives on Earth, such as their behavior, physiology, development, and overall well-being. Aquatic environments typically have a greater influence on aquatic animals compared to terrestrial environments on terrestrial animals. Certain environmental parameters, such as water temperature, dissolved oxygen, turbidity, and food availability, can influence fish movement, with fish generally moving towards areas with higher food availability. To understand the importance of environmental factors on the fish (Labiobarbus festivus and Osteochilus hasseltii) catching efficiency of gillnets, a 12-month (January and December 2016) study was conducted at three sampling sites in Lake Kenyir, northern Malaysia. Fish were caught once in every month using gillnets (each 200 m long, 2 m deep) of three different mesh sizes (38-, 51-, or 76-mm mesh), each of which was deployed in duplicate at the surface of one of three randomly selected sites, concurrent with measuring various environmental parameters and the abundance of phytoplankton and benthic macroinvertebrates. Data were analyzed statistically using the redundancy analyses (RDA) and permutational multivariate analysis of variance (PERMANOVA). Results indicated that the catches of L. festivus were positively influenced by water turbidity with no seasonal effects, while the density of phytoplankton positively influenced the catches of O. hasseltii. The catches of O. hasseltii were somewhat size specific with positive and negative effects of the monsoon on small and large fish, respectively. Such species-specific differences were attributed to life histories, and although L. festivus might be best sought during any period of turbidity. In contrast, larger O. hasseltii might be best sought during non-monsoon period concurrent with greater catches. The observed results can be valuable for ecological monitoring and adjusting gillnet fishing efforts in management plans related to these fishes, particularly in response to climate change.
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