Species of Concern
What species of marine mammals, sea turtles and seabirds occur and may be at risk for capture or interaction with fisheries?
According to a 1994 report by Vidal et al., the only recorded marine mammal interaction with fishing gear in Trinidad and Tobago was the entanglement of a killer whale in a gillnet. The animal died after struggling for more than an hour. The report, which is based on very limited data, also states that bottlenose dolphins and humpback whales are also at risk.
Visual and acoustic surveys for marine mammals were conducted in the spring of 1995, 1996, 2000 and 2006, off the coasts of Dominica, Martinique, Guadeloupe, Grenada, and Trinidad and Tobago (SC/58/SM24 Sm Cet 2006). These surveys encountered 13 species of small cetaceans. The Small Cetaceans report provides a comprehensive look at what species of marine mammals are present in the waters of various Caribbean islands, and identifies threats or potential threats for some of these species. While this is not a direct bycatch mitigation project, it provides a foundation to identify species of concern or areas in need of further research before a proper bycatch mitigation project can be planned and implemented. From these studies, the species found in the waters of Trinidad and Tobago, and information about their populations and threats are as follows:
The Small Cetaceans report indicated that the Fraser’s dolphin is found off the central coast of Venezuela, which means that it could also be found in or around Trinidadian waters. This species is exceptionally vulnerable to entanglement in driftnets. Given the gillnet fishery for kingfish, this species could be at risk in Trinidad.
In 1988, an individual killer whale (Orcinus orca) from a group of about 15 animals became entangled in a fishing net in the Gulf of Paria.
Most marine mammal exploitation in Trinidad and Tobago occurred from 1826-1865 as part of an intense, shore-based endeavor of local elites who hired slaves to do most of the work (Romero et al. 2002). Exploitation trends in Trinidad and Tobago differ significantly from the marine mammal exploitation of the surrounding countries of Venezuela, Grenada, and St. Vincent and the Grenadines. Whales, mostly humpback whales, were targeted directly and utilized for oil, meat and whalebone (Romero et al. 2002). Direct dolphin fisheries are rare and have mostly been limited to the opportunistic use of incidental catches. As of Romero et al.’s 2002 report, whaling is no longer practiced in Trinidad and Tobago, and ended long ago when local populations declined or went extinct. During the time that whaling did occur, there are records of at least 500 whales being hunted between 1826 and 1865. Although considered endangered, all cetaceans lack legal protection under either the Fisheries Act of 1980 or the Conservation Wildlife Act of 1980.
Dolphins have historically been rare in Trinidad and Tobago’s waters, and most reports are related to accidental nettings, although there are occasional reports of harpooning ‘porpoises’ (Romero et al. 2002). Dolphins caught as bycatch are mostly captured in Italian seines and gillnets. The main species are Stenella spp. and Tursiops truncatus. Most dolphins are dead when captured, but if they are alive, they are killed. Most are sold in the wholesale market, and occasionally by the side of the road. The orca, Orcinus orca, is reportedly the largest animal incidentally captured and kept by a drift gillnet. This occurred in 1987 (Romero et al. 2002). Also in 1987, a pod of 15 adult and 2 calf short-finned pilot whales (Globicephala macrorhynchus) stranded on the North Coast at La Filette. All but the two calves and one adult were returned to sea – the others were sold at a fish market.
Manatees have been harpooned for their meat, oil, and hide from Colonial times until relatively recently, as indicated by Trinidadian officials who report illegal hunting of manatees as late as 1980 (Romero et al. 2002). There is a report from 1990 of a manatee accidentally caught in a fishing net and butchered. Unlike cetaceans, the manatee is protected under Chapter 61:01 of the Conservation of Wildlife Act, and cannot be hunted at any time. Its habitat is also protected under the Forest Act Chapter 66:01 (Romero et al. 2002). However, manatees are threatened with extinction, as there is only a small population with approximately 18 individuals (in 1997) living in the Nariva Swamp, and poaching and habitat destruction continue.
A comprehensive list of marine mammals that have ranges which include the waters of Trinidad and Tobago, and which may be found there, can be found in Appendix 3.
The incidental capture of leatherback turtles in artisanal gillnets has been examined in multiple studies, and Eckert and Lien (1999) found that this may be the largest single source of mortality for leatherbacks in Trinidad and Tobago (Lee Lum 2003). Although a greater number of leatherbacks have been found in the surface-set multifilament gillnets, there is greater mortality of those caught in the bottom-set monofilament nets (Gass 2006). Fishermen often kill sea turtles that are caught in their nets out of frustration from the destroyed nets.
I found no information on the interaction between fisheries and seabirds for Trinidad and Tobago.