Length-weight relationships of fish from sandy beaches

Area of Science:

• Ichthyology
• Aquatic Ecology
• Amazonian Biodiversity

Background:

• Length-weight relationships (LWRs) are crucial for fish stock assessment and ecological studies.
• Limited LWR data exists for many fish species in the Amazon basin, hindering conservation and management efforts.
• The lower Negro River basin is a vital ecosystem with high fish diversity, yet understudied regarding fish population parameters.

Purpose of the Study:

• To estimate the length-weight relationships (LWRs) for 16 fish species from the lower Negro River basin.
• To provide updated maximum length data for six specific fish species.
• To contribute novel LWR parameters for 15 fish species, expanding the existing knowledge base.

Main Methods:

• Fish specimens were collected monthly (October-November 2016) from sandy beach shores using a 20 m trawl net.
• Standard length (SL) and total weight (TW) were measured with high precision (0.1 cm and 0.01 g, respectively).
• The parameters 'a' and 'b' of the length-weight equation WT = a.LTb were estimated for each species.

Main Results:

• Estimated 'a' values ranged from 0.0018 to 0.0226, and 'b' values ranged from 2.5271 to 3.3244 across the studied species.
• New maximum length data were reported for Amazonsprattus scintilla, Brycon pesu, Moenkhausia megalops, Pachyurus paucirastrus, Reganella depressa, and Trachydoras microstomus.
• Length-weight relationships parameters were newly reported for 15 of the 16 investigated fish species.

Conclusions:

• The study successfully estimated LWRs for 16 fish species, providing essential data for the lower Negro River basin.
• The findings significantly expand the available LWR data for Amazonian fish, particularly for underrepresented species.
• This research offers valuable baseline information for future ecological assessments, fisheries management, and conservation strategies in the region.