Acta Ichthyologica et Piscatoria 50(4): 493-500, doi: 10.3750/AIEP/02965
Rapid reproductive analysis and weight-length relation of the humpnose big-eye bream, Monotaxis grandoculis (Actinopterygii: Perciformes: Lethrinidae), from Micronesia with implications for fisheries
expand article infoK. Longenecker, A. Gill, M. Kelokelo, R. Langston, T.J. Donaldson, E.C. Franklin

Corresponding author: K. Longenecker

© K. Longenecker, A. Gill, M. Kelokelo, R. Langston, T.J. Donaldson, E.C. Franklin.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Longenecker K, Gill A, Kelokelo M, Langston R, Donaldson T, Franklin E (2020) Rapid reproductive analysis and weight-length relation of the humpnose big-eye bream, Monotaxis grandoculis (Actinopterygii: Perciformes: Lethrinidae), from Micronesia with implications for fisheries. Acta Ichthyologica et Piscatoria 50(4): 493-500. https://doi.org/10.3750/AIEP/02965
Open Access
Abstract
We present a weight–length relation and use rapid and low-cost histological methods to generate preliminary reproductive parameters for Monotaxis grandoculis (Forsskål, 1775), based on specimens collected in Guam and Pohnpei [W = 0.033(FL)2.91]. We estimated female L50 at 30.0 cm FL and male L50 at 35.4 cm FL. The species is gonochoric.  Overall and operational sex ratios were not significantly different from 1:1; however, among mature individuals, the proportion of females was an inverse function of length with no females > 33.5 cm FL but males to 44.5 cm FL. Batch fecundity was an exponential function of length but, because females were absent in the largest size classes, the highest per capita egg production was by individuals at 31.7 cm FL, only 71.2% of maximum observed specimen length. Boat-based creel surveys in Guam showed that the mean length of M. grandoculis in the catch decreased below both female and male L50 from 2010 to 2019, suggesting a significant decline in spawning stock biomass.
Keywords
maturation, sex ratio, fecundity, Pohnpei, Guam