Sea cucumbers play a critical role in maintaining healthy marine ecosystems. Sea cucumbers are also a key source of income for millions of small-scale fishers worldwide. The lucrative nature of this industry has led to severe reductions in sea cucumber populations in numerous regions globally. A large proportion of sea cucumber fisheries are located in developing countries, which present unique challenges to management, including addressing highly decentralized methods of extraction and processing, limited economic and technological resources for governance and, in many cases, a high dependency on sea cucumbers as a primary source of income for small-scale coastal fishers. In this review, we review the benefits and challenges of seven categories of sea cucumber management strategies used globally in developing countries, including gear restrictions, size and weight limits, effort and catch controls, temporal closures, area closures, value chain licensing and territorial use rights in fisheries. We conclude that sea cucumber management in developing countries could benefit from focusing regulatory solutions on narrowed parts of the value chain, coupling production-based management strategies with processing and export regulations and providing avenues for local fishers to inform policy at the local, regional and national levels.

Thyone and Havelockia are worldwide-distributed genera represented in the Western Atlantic by eight and three species, respectively. In this paper, we describe two new shallow-water species from the Brazilian coast: Thyone waltinhoi sp. nov. and Havelockia oraneae sp. nov. These genera are very similar morphologically but the presence of subdivisions in their calcareous rings separates them into different families, Thyone in Phyllophoridae and Havelockia in Sclerodactylidae. To observe the presence of subdivisions, we submerged the calcareous rings in an iodine solution prior to morphological analyses. Thyone waltinhoi sp. nov. differs from its Western Atlantic congeners in its dermal ossicles and Havelockia oraneae sp. nov. differs from its South-western Atlantic congeners in the composition of its introvert ossicles. In addition to species descriptions, illustrations and morphological diagnoses of both genera are provided, along with a synoptic table of their Western Atlantic species, and a discussion of the taxonomic significance of the dermal ossicles and the calcareous ring.

Animals develop behavioural strategies throughout life to improve their survival in nature. Juvenile activity and behaviour of the commercial tropical sea cucumber Stichopus cf. horrens were examined considering factors that may influence survival at this critical developmental stage. Wild juveniles were observed in situ to describe diel activity and movement. Wild and hatchery-reared juveniles were observed in the laboratory to evaluate the influence of different light-dark cycles and microhabitats on feeding and sheltering behaviour. All juveniles (4–54 g) displayed a distinct nocturnal activity pattern both in the field and laboratory. Nocturnal activity was strongly associated with feeding and locomotion. Wild and hatchery-reared juveniles were most active at night, displayed intermediate activity during twilight, and minimal to no activity during daytime. Movement rates of wild juveniles in situ were significantly influenced by time and size to a lesser extent. Under constant light and constant dark for 48 h, juvenile feeding rhythm was endogenously controlled and strongly entrained to natural light-dark cycles. Sheltering was directly affected by light and linked to strong phototactic and thigmotactic reflexes. Juveniles preferred vegetation as shelter compared to coral, sand or open space, and showed equal preference for seagrass and macroalgae. Deviations in behaviour of hatchery-reared juveniles under laboratory conditions indicate some degree of acclimation to an artificial environment with minimal threats and a decreased sensitivity to light. The implications of nocturnal feeding, light-induced sheltering, shelter preferences and acclimation to artificial conditions are discussed in relation to juvenile survival in nature and potential restocking of the species.

Reproductive aspects of the sea cucumber Athyonidium chilensis were studied over a year in Valdivia, Chile, through gonad index (GI) analysis, macro- and microscopic analysis of the gonads, fecundity and size at first sexual maturity estimations. We also explored the reliability of live size estimators for their use in fisheries. Athyonidium chilensis showed continuous gametogenesis and spawning individuals could be found throughout the year. However, spring was the main reproductive time, where an important GI decrease coincided with enhanced spawning activity evidenced through histology. GIs recovered in summer, and new signs of enhanced spawning activity were observed towards autumn (April 2008). GI peaks were observed in August 2007 and March 2008 for females (22.8 and 24.4% respectively) and September 2007 and March 2008 for males (31.9 and 25.9% respectively). Low mean GIs occurred in May and December 2007 for females (15.2 and 11.6% respectively) and May and October 2007 for males (12.7 and 14.1% respectively). Males reached sexual maturity at a smaller size than females (males: 21.2 g, females: 43.7 g eviscerated weight), and mature females showed a high mean absolute fecundity for a species with lecithotrophic larval development (6.31 × 105 ± 1.97 × 105 SD). For fisheries, we recommend a minimum catch size over 237.89 g drained weight to ensure that caught individuals are sexually mature. This study provides relevant information for the conservation and fishery management of A. chilensis. Continuous gametogenesis and high fecundity make this species particularly suitable for aquaculture in southern Chile.

Fatty acids (FA) are a non-protein energy source and can act as trophic biomarkers in benthic food webs. We analysed the FA profiles of sea cucumber Apostichopus japonicus, comparing tissues of body wall, gut sediment and ovaries in two habitats. Rongcheng Bay: kelp raft cultivation area with high organic matter in sediment; Laoshan Bay: strong current with low sediment organic matter. The results showed that body wall and ovary tissues were rich in long chain polyunsaturated FA (LC-PUFA), which contributed ~31% to the FA dissimilarity between the two tissues. SIMPER (similarity percentages routine) results showed that C20:5ω3 (EPA), C18:1ω7, C20:4ω6 (AA), C16:0, C14:1 and C20:1ω11 contributed to dissimilarity between the body wall and ovary tissues, while 16:1ω7, 20:5ω3, C16:0, C18:1ω7, C18:0 and C14:1 contributed more to the dissimilarity of body wall tissues between the two habitats. FA biomarkers showed that sea cucumbers from the two habitats had different food sources, with brown kelp and vascular plants being the main food for sea cucumbers in Rongcheng and diatoms for those in Laoshan. To better understand differences in FA composition in sea cucumbers, more research is needed examining a wider diversity of tissue types and habitats.

In Pakistan, although the sea cucumber fishery has not yet been developed, Holothuria arenicola is abundant on its coast. Nineteen months of sampling was carried out to study the population structure, allometric relationships and reproductive status of H. arenicola stocks in Manora and Buleji rocky shores. All measured biometric characters showed significant temporal variations and width/length, weight/length, gutted weight/length and gutted weight/weight relationships followed negative allometry, indicating a change in body shape as the animal grows. Length-frequency distribution analysis was bimodal in both summer and autumn consisting of small-sized and medium-sized individuals while in winter and spring three modes were found at Manora. At Buleji, the population was unimodal in all seasons consisting of small-sized individuals. Sex in H. arenicola cannot be determined externally but can be identified on examination of gonad colour which is orange-like in females and creamy yellow in males. The sex was further confirmed on histological examination and maturation was divided into five stages, i.e. undetermined, early developing, late developing, mature and partially spawned. The sex ratio in H. arenicola was approximately 1:1 and increase in gonad index was observed during spring and early summer, followed by a decrease in GI in autumn and winter, which showed the spawning followed by resting phase. The GI showed a significant negative correlation with salinity and non-significant correlation with temperature. There is a need to undertake more biological/ecological studies on H. arenicola in order to take effective measures for its management.

In this paper, we record the occurrence for the first time of two sea cucumber species from the Persian Gulf (Hormuz Island). Sea cucumber samples were collected in the sub-tidal zone of the island during low tide. Species identification was accomplished using morphological keys and a review of their ossicles. The collected specimens provide evidence that Holothuria bacilli and Holothuria insignis are present in the Persian Gulf waters.

Albinism is a hereditary lack of pigmentation caused by deficiencies in enzymes related to the metabolism of melanin. This mutation is present in marine vertebrates and invertebrates, including the Holothuroidea class; nevertheless, information about the occurrence of albinism in these kinds of echinoderms is scarce and refers to species from temperate and cold regions of the ocean. In 2013, we observed two albino individuals of Isostichopus fuscus, one at Loreto (25°45′54″N, 111°14′36″W) and the second one at Los Angeles Bay (29°02′54″N, 113°29′49″W). This is the first documented record of albinism for this species.

Sea cucumbers (phylum Echinodermata) are common members of benthic communities in many marine ecosystems. They function as nutrient recyclers and bioturbators of soft bottoms, and are preyed upon by birds, fishes, mollusks, crustaceans and other taxa. In the Central Mexican Pacific, Islas Marietas harbours a complex and diverse community of corals and benthic invertebrates, with a particularly well-represented assemblage of echinoderms. However, little is known about the diversity of holothurians in the area. Between 2012 and 2014 a bimonthly census was conducted at Islas Marietas, and seven species were recorded for the first time at this location: Holothuria (Halodeima) inornata, Holothuria (Mertensiothuria) hilla, Holothuria (Platyperona) difficilis, Neocucumis veleronis, Lissothuria ornata, Afrocucumis ovulum and Pachythyone pseudolugubris. The absence of previous records of these species may be associated with their low densities and cryptic habits. This report acts to fill a critical knowledge gap in the distribution of holothurians in the eastern tropical Pacific and highlights the under-appreciated biodiversity of this Natural Protected Area.

Many sea cucumber fisheries have dramatically declined worldwide due to rapid overexploitation and ineffective management. This study designed an innovative management strategy for small-scale, data-limited sea cucumber fisheries in Pacific Island countries. Firstly, a local quota-based comanagement system was implemented in New Caledonia to manage a small-scale sandfish Holothuria scabra fishery. A habitat map derived from high-resolution satellite imagery was used to stratify survey sampling and assess the harvestable stock biomass. The latter has been monitored as the reference biomass (RB) since 2008 and repeatedly used by the local fishers’ organization and Fisheries Department officers to set adaptive total allowable catches and regulations of fishing effort. Results showed the excellent performance of this fishery between 2008 and 2012, both biologically (167% increase in total stock biomass) and economically (146% increase in annual returns from catches). Secondly, the assessment of the RB was generalized to multispecies sea cucumber fisheries in Vanuatu in 2011 before the proposed lifting of a five-year national moratorium. Building upon these practical case studies in New Caledonia and Vanuatu, this paper outlines an operational framework to inform sea cucumber fisheries policy in these two countries and discusses the upscaling of the proposed management strategy.

In Iran, the sandfish, Holothuria scabra is the most exploited sea cucumber species which is harvested at Qeshm Island because of the high demand from Indian and Bangladeshi traders. Some specimens of the sea cucumber were collected by snorkellers diving at depth of 5 m at Qeshm Island in the Persian Gulf. An examination identified the sea cucumbers as H. scabra. Previous research has not found this species in the Persian Gulf. This report is the first to document the highly valued commercial sea cucumber in the Persian Gulf region.

This study has been conducted in order to identify the present species in the northern part of the Persian Gulf. Samples were collected on the sub tidal zone of Larak Island (Persian Gulf) via SCUBA diving in July 2011. The literature review on the distribution revealed that this is the first report of Holothuria hilla from Larak Island. The species identification was made using morphological keys and review of their ossicles.

In Iran, sea cucumbers are not well known and they are not consumed as food. With this and the lack of scientific knowledge about them, this study has been conducted in order to identify the present species in the northern part of the Persian Gulf. Samples were collected in the sub-tidal zone of Larak Island (Persian Gulf) via SCUBA diving in August 2011. The literature review on the distribution revealed that this is the first report of Holothuria impatiens from Larak Island (Persian Gulf). The species identification was made using morphological keys and review of their ossicles.

Analysis of ecological baseline data collected for key resource species within the Galapagos Marine Reserve indicates that variation in animal density associated with the location of fully protected zones can be comparable to protected area effects. Even with a high level of interspersion between conservation, tourism and fishing management zones, major differences in densities of economically important species were evident between zone types prior to enforcement of fishing restrictions. Densities of the most valuable fishery resource, sea cucumbers, were three times higher in zones that remained open to fishing compared to ‘no-take’ conservation zones, and densities of sharks were five times higher in tourism zones than fishing or conservation zones. These results highlight bias in the socio-political processes that can accompany selection of marine protected areas, where fishers attempt to minimize perceived impacts on their livelihood by locating large protected zones in resource-poor areas, and tourism operators and sport divers argue for protection of areas containing atypically-interesting features. Bias in the location of fully protected zones can seriously confound ‘control-impact’ field investigations when data prior to prohibitions on fishing are lacking, including meta-analyses, which are dominated by such potentially systematically biased studies.