Version 1
: Received: 30 October 2024 / Approved: 31 October 2024 / Online: 31 October 2024 (08:37:37 CET)
How to cite:
McClanahan, T.; Kiprono Kosgei, J.; Tom Humphries, A. Fisheries Sustainability Eroded by the Loss of Vulnerable Dominant Taxa and Insufficient Compensatory Production in a Coral Reef Seascape. Preprints2024, 2024102514. https://doi.org/10.20944/preprints202410.2514.v1
McClanahan, T.; Kiprono Kosgei, J.; Tom Humphries, A. Fisheries Sustainability Eroded by the Loss of Vulnerable Dominant Taxa and Insufficient Compensatory Production in a Coral Reef Seascape. Preprints 2024, 2024102514. https://doi.org/10.20944/preprints202410.2514.v1
McClanahan, T.; Kiprono Kosgei, J.; Tom Humphries, A. Fisheries Sustainability Eroded by the Loss of Vulnerable Dominant Taxa and Insufficient Compensatory Production in a Coral Reef Seascape. Preprints2024, 2024102514. https://doi.org/10.20944/preprints202410.2514.v1
APA Style
McClanahan, T., Kiprono Kosgei, J., & Tom Humphries, A. (2024). Fisheries Sustainability Eroded by the Loss of Vulnerable Dominant Taxa and Insufficient Compensatory Production in a Coral Reef Seascape. Preprints. https://doi.org/10.20944/preprints202410.2514.v1
Chicago/Turabian Style
McClanahan, T., Jesse Kiprono Kosgei and Austin Tom Humphries. 2024 "Fisheries Sustainability Eroded by the Loss of Vulnerable Dominant Taxa and Insufficient Compensatory Production in a Coral Reef Seascape" Preprints. https://doi.org/10.20944/preprints202410.2514.v1
Abstract
The status of tropical fisheries is poorly known because the existing methodological choices have variable outcomes and recommendations. Therefore, multiple approaches to estimating sustainability were compared, namely fisheries independent stock biomass and recovery rates, fisheries dependent landed catches, balanced harvest and gear use metrics, and fish length measurements. Unfished biomass recovery time series was established by a 45-year stock recovery relationship from 7 fisheries reserves and compared to catch and length-based estimates of sustainability. The logistic production rates (r = 0.10 ± 0.06 95% CI) and maximum equilibrium total biomass (150 ± 30 tons/km2) indicated a broad range of potential maximum sustainable yields but likely ranging from 1.1 to 3.9 (95% CI; mean = 3.8) tons/km2/year. In contrast, mean annual biomass growth rates in reserves was lower but less variable than surplus production estimates, ranging from 2.1 to 3.5 (mean=2.8 tons/km2/year). Realized catches at landing sites was lower still, ranging from 1.43 to 1.52 (mean=1.48± 0.2 tons/km2/y). Differences were largely attributable to changes in taxonomic composition and an imbalance in the proportionality of production potential versus actual capture rates. Differences in the vulnerability of taxa to fishing and a lack of compensatory increased production among fishing resistant taxa could largely account for the lost potential production. Large proportional losses of catch were measured among snappers, unicorn fish, sweetlips, goatfish, and soldierfish, while smaller proportional gains in the catch were found among resident herbivorous rabbitfish, parrotfish, and groupers. Many of these declining taxa had vulnerable schooling life histories likely to require special habitat and reserve characteristics. Evaluations of sustainability from length measurements found 17 or 7% of total and 12% of caught species had a minimum sufficient sample sizes (>30 individuals, 413 catches, 2299 individuals, and 144 species) to evaluate length and spawning metrics of sustainability. Seven of these species met length-based and 3 meet spawning potential ratio thresholds for sustainability. Consequently, length-based evaluations were unable to evaluate the sustainability of the larger community. Recommendations include a management focus on the recovery of “ghost taxa”, species abundant in the oldest reserve but not contributing to fisheries yields.
Keywords
balanced harvest; community biomass; fish life histories; gear management; ghost taxa; marine reserve benchmarks; surplus production models
Subject
Biology and Life Sciences, Aquatic Science
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
