Restoration of Stocks of the Sea Cucumber <i>Holothuria fuscogilva</i> in the Red Sea with Transplanted Wild Juveniles

Abstract

Over the last decade, holothuroid sea cucumbers in the Gulf of Aqaba of the Red Sea have been the target of continuous fishing. This has severely depleted sea cucumber stocks, especially the high-value species such as Holothuria fuscogilva. The present work demonstrates that restocking populations of H. fuscogilva that are at critically and chronically low levels by transplanting wild-captured juveniles can be effective. Juveniles were translocated from a robust population at Pharoan Island and released into two sites (Wadi Quny and Hidden Bay). Population density, growth rate and mortality at the original and two release sites were monitored for 2 yrs. The Pharoan population density was highest, with H. fuscogilva showing a strong preference for sandy habitat (21.3 -18.4 ind./100m 2 ), over seagrasses (3.6 -2.5 ind./100m 2 ) and corals (0.9 -1.7 ind./100m 2 ). The restocked population at Wadi Quny increased from 2.6 to 9.8 ind./100m 2 from 2013-2015. In contrast, density at Hidden Bay decreased from 2.8 to only 0.1 ind./100m 2 in the first year. Sea cucumbers in the restocked population at Wadi Quny had higher growth rates (0.65 -1.29 cm/month) compared to the original population at Pharoan Island (0.21 -0.45 cm/month), while Hidden Bay showed a negative growth rate. Mortality was low at Pharoan Island (1% -2%) and Wadi Quny (0.5% -0.75%), but high at Hidden Bay (49% -100% in the first year). There was a negative relationship between mortality and size (P = 0.003). The restocking of H. fuscogilva populations using wild-captured juveniles was very successful at Wadi Quny but a failure at Hidden Bay.All applicable international, national and/or institutional guidelines for the care and use of animals were followed by the authors.

First trial of wild juvenile collection of tropical sea cucumbers from settling larvae, using coconut fibre from waste husks in Solomon Islands: A new conservation tool

“…As WJC only harvests a part of a naturally settled population, there is little concern about genetic disturbance and negative impacts on natural rates of settlement and the population growth of existing sea cucumbers, as both WJC and the subsequent release occur in a relatively narrow community territory. On the other hand, for the same reason WJC alone is insufficient to demonstrate conservation effects and needs to be combined with measures to enhance the survival and growth of juveniles after collection, for example, with artificial shelters (Gamboa‐Álvarez et al, 2021) or transplantation to favourable environments (Eckert, 2007; Slater & Carton, 2007; Lee, Byrne & Uthicke, 2008; Hasan & Johnson, 2019). In addition, more biological data are necessary to increase the efficiency of WJC, such as defining the optimal spawning seasons (Ramofafia et al, 2000; Ramofafia, Byrne & Battaglene, 2001; Ramofafia, Byrne & Battaglene, 2003), vertical migration patterns (Kashenko, 2002) and preferred settlement environments of the larvae (Hamel & Mercier, 1996; Mercier, Battaglene & Hame, 2000).…”

“…As WJC only harvests a part of a naturally settled population, there is little concern about genetic disturbance and negative impacts on natural rates of settlement and the population growth of existing sea cucumbers, as both WJC and the subsequent release occur in a relatively narrow community territory. On the other hand, for the same reason WJC alone is insufficient to demonstrate conservation effects and needs to be combined with measures to enhance the survival and growth of juveniles after collection, for example, with artificial shelters (Gamboa-Alvarez et al, 2021) or transplantation to favourable environments (Eckert, 2007;Slater & Carton, 2007;Lee, Byrne & Uthicke, 2008;Hasan & Johnson, 2019).…”

Sea Cucumbers (Holothuroidea) of Northeastern and Western Mindanao, Philippines: The Potential Role of Marine Protected Areas in Maintaining Diversity and Abundance

“…MPA highlights the importance of protection in maintaining viable stocks of commercial sea cucumbers. Population densities of H. fuscogilva as high as 1,800-2,130 indivs/ha were recently reported on sandy areas inside the well-enforced Pharoan MPA in the Red Sea (Hassan and Johnson, 2019) while populations have collapsed in unprotected sites.…”