Marine environment

2.1 Protect and manage East Pacific green turtle populations in the marine habitat.

Protection of turtles in the marine environment is a priority that is often overlooked as enforcement is difficult and quantification of the problem problematic. However, 99% of a turtle’s life is spent at sea; thus, recovery must include significant efforts to protect turtles at that time. As their distribution in the marine habitat of the U.S. Pacific is limited, we must encourage and support recovery efforts in other Pacific nations where the turtle species is found.

2.1.1 Eliminate directed take of turtles.

Direct take of turtles was identified as a severe threat to population recovery in the Pacific Ocean and must be eliminated if sea turtles are to recover. Reduce directed take of turtles through public education and information.

While increased law enforcement will be effective in the short term, without support of the local populace, regulations will become ineffective. Education of the public as to the value of conserving sea turtles, is a very effective way of sustaining recovery efforts and providing support for enforcement of management regulations. (Also see Section 4). Increase the enforcement of protective laws on the part of law enforcement and the courts.

One of the major threats identified for turtle populations in the Pacific was the illegal harvest of turtles both on the nesting beach and in the water. Rigorous efforts in law enforcement should be undertaken immediately to reduce this source of mortality. Such efforts need to include training of enforcement personnel in the importance of protecting turtles, as well as supplying such personnel with adequate logistical support (boats, communication and surveillance equipment etc.). Judges and prosecutors must also be educated in the importance of these matters.

2.1.2 Determine distribution, abundance, and status in the marine environment.

In its review of information on sea turtle populations in the Pacific, the Recovery Team found that lack of accurate information on distribution and abundance was one of the greatest threats to sea turtle populations. While excellent information on nesting for some areas of Mexico is available, particularly in Michoacán, there is a general lack of information on the regional population size and status. We consider that gathering of basic information on distribution and abundance should be a very high priority activity toward the recovery of East Pacific green turtle populations. Determine the distribution and abundance of post-hatchlings, juveniles and adults.

While little is known about the distribution of nesting beaches for the East Pacific green turtle, even less is understood about distribution of foraging adult and juvenile populations. Quantitative surveys of foraging areas to determine their abundance, and to identify essential habitat is of significant importance for restoration of East Pacific green turtle populations. Determine adult migration routes and inter-nesting movements.

Like all species of sea turtle (with the possible exception of the Flatback turtle, Natator depressus), East Pacific green turtles migrate from foraging grounds to nesting beaches. These migrations often mean that the turtles move through a variety of political jurisdictions where regulations regarding the stewardship of the species may vary. To preclude the problem of contradictory management strategies by these various jurisdictions, it is important to determine the migration routes East Pacific green turtles follow between nesting and foraging areas. Satellite telemetry studies of both males and females are needed. Determine growth rates and survivorship of hatchlings, juveniles, and adults, and age at sexual maturity.

Understanding the rates of growth and survivorship of turtle populations is crucial to the development of appropriate population models. Such models are important in understanding population status and how best to efficiently apply management efforts, in restoring depleted populations. For example, the application of stagebased modeling (Crouse et al. 1987) indicated that not enough effort was being expended on protecting juvenile sized loggerhead sea turtles in the southeastern United States and that without such protection, extensive nesting beach protection was having less positive benefit. A similar approach to understanding East Pacific green turtle populations should be undertaken, and used to guide restoration policy. Identify current or potential threats to adults and juveniles on foraging grounds.

Little is known about threats to foraging populations of East Pacific green turtles. Studies on such threats should be undertaken immediately.

2.1.3 Reduce the effects of entanglement and ingestion of marine debris.

Entanglement due to abandoned or unmonitored fishing gear, as well as the ingestion of man-made debris is a significant problem in the marine environment. Evaluate the extent to which sea turtles ingest persistent debris and become entangled.

Quantification of the extent to which sea turtles are impacted by marine debris should be undertaken as a first step to mitigating or preventing such impacts. The benefits of such work are that it allows the prioritization of recovery activities and it allows the activities to be efficiently targeted at the problem. Evaluate the effects of entanglement and ingestion of persistent debris on health and viability of sea turtles.

Because of the remote nature of turtle/debris interactions, the acute and chronic effects of such interaction are not often understood. Turtles may not die immediately after ingesting certain materials, but may become debilitated. Studies to further understand the impacts of such interactions, and what age classes are affected most severely, should be undertaken immediately. As with quantifying the extent to which sea turtles ingest debris, such a program allows recovery efforts to be more efficient. Formulate and implement measures to reduce or eliminate persistent debris and sources of entanglement in the marine environment.

Once the problem of marine debris has been identified and quantified, it is important to implement (and enforce) a program to reduce the amount of debris in the marine environment, ie. removing the problem entirely.

2.1.4 Monitor and reduce incidental mortality in the commercial and recreational fisheries.

For some areas, incidental take in fisheries has been identified as a severe threat. These mortalities are often associated with international fleets operating on the high seas, but for the coastal dwelling East Pacific green turtle it is probably most significant in nearshore waters. Monitoring of turtle take by fisheries is extremely important for two reasons. First, it allows resource managers a means to quantify the extent of the problem, and by the very act of monitoring, tends to cause commercial fishermen to be more aware of the concern over incidental take, and thereby encourage reduced take. The choice method for monitoring take is through the use of an unbiased observer program. Voluntary logbooks have not proven a reliable technique for quantifying incidental catch in commercial fisheries. Implementation of mortality reduction activities includes the use of TEDs in shrimp trawler fisheries.

2.1.5 Eliminate the harassment of turtles at sea through public education and enforcement.

Activities such as “petting” turtles and chasing them while snorkeling and scuba diving, water skiing, jet skis, vessel traffic, and vessel anchoring may disturb or displace turtles. These factors should be regulated or controlled to eliminate negative impacts, especially in sensitive and high density foraging and resting areas.

2.1.6 Study the impact of diseases on turtles.

Little is known about diseases in sea turtles, but there has been recent evidence that it may be a limiting factor in certain populations. Disease origin and transmission may not be limited to the marine environment. Determine prevalence of fibropapillomatosis in population.

Debilitating and life threatening tumors are known to occur in populations of green turtles. The magnitude of this disease during recent years has increased substantially in some areas although the extent of the disease is unknown in the east Pacific green turtle. The etiology of the disease and effects as they relate to the viability of the population are presently unknown and need to be studied. Investigate parasites and other infectious agents.

A variety of other diseases and parasites may be affecting sea turtles. The prevalence of such infections, their impact on sea turtles, and modes of transmissions need to be studied. Parasites include internal parasites such as blood flukes, external parasites such as leeches (Ozobranchus) and burrowing barnacles (Stephanolepas), and certain bacterial infections such as Vibrios.

2.1.7 Maintain carcass stranding network.

Stranding networks are operated generally by volunteers who monitor beaches for stranded animals. Such networks can be useful for alerting managers to incidents causing high mortality, such as an increased fishery take or disease problems, as well as providing some basic biological data.

2.1.8 Centralize administration and coordination of tagging programs.

In general, government resource management agencies can provide the continuity required to coordinate tagging programs. The responsibility of any such agency is that they act as a central distribution point for tags, tagging training and database management. It is critically important that the coordinating agency:

  1. provides adequate staff to keep the program organized and respond to tag returns immediately, and
  2. remain in existence for many years (20+). Without such a commitment, tagging programs have very limited usefulness, and before initiation of such a program it should be considered carefully on its scientific merits. It must be remembered that sea turtles are long-lived animals, and the most valuable information yielded by any tagging program comes from turtles which have carried identification tags for many years. Short-term tagging projects are at best very limited in the information they yield and at worst are nothing more than a form of undue harassment to the turtles.

Centralization of tag records is useful as it makes the most efficient use of limited personnel resources, allows standardization of techniques, and can act as a screening mechanism to ensure that tagging is done for valid scientific reasons.

2.2 Protect and manage marine habitat, including foraging habitats.

East Pacific green turtles inhabit a variety of marine habitats, although we are most familiar with their coastal habitat. Increased human presence in this and other sea turtle habitats have contributed to habitat degradation, primarily by coastal construction, increased recreational and fisheries use, and increased industrialization. Habitat loss and degradation must be prevented or slowed.

2.2.1 Identify important marine habitats.

These areas may include hatchling, juvenile and adult foraging areas and migratory range for all age classes. (Many of these areas will first need to be identified through actions in Section and

2.2.2 Ensure the long-term protection of marine habitat.

Once marine habitats are identified, sea turtle range, refugia and foraging habitats (Sargassum beds, coral reefs or seagrass and algal beds, estuarine habitats) need to be protected to ensure long-term survival for the species. Habitats identified as important or critical should be designated as marine sanctuaries or preserves, while others may require close monitoring. The public needs to be educated on the importance of preserving these habitats.

2.2.3 Assess and prevent the degradation or destruction of reefs and seagrass beds caused by boat groundings, anchoring, and trampling by fishermen and divers.

This is not an issue for the East Pacific green turtle due to minimum amounts of such habitat within the species distribution.

2.2.4 Prevent the degradation of reef habitat caused by environmental contaminants such as sewage and other pollutants.

This is not an issue for the East Pacific green turtle due to minimum amounts of such habitat within the species distribution.

2.2.5 Prevent the degradation or destruction of marine habitats caused by dredging or disposal activities.

Dredging causes mechanical destruction of benthic habitats, adds suspended sediments that may damage algae and seagrasses and disposal of dredged materials smothers existing flora and fauna. Some types of dredging also kill turtles directly.

2.2.6 Prevent the degradation or destruction of important habitats caused by upland and coastal erosion and siltation.

These processes, often made worse by coastal construction, adversely affect coastal habitats by disrupting vital trophic processes, reducing productivity and reducing species diversity. Minimum water standards upstream must be maintained. Land-use decisions must take this into account and associated projects where erosion and siltation occur must be monitored.

2.2.7 Prevent the degradation or destruction of reefs by dynamite fishing and construction blasting.

Blasting of any nature physically damages reefs and may kill turtles. It must be monitored and/or restricted.

2.2.8 Prevent the degradation of coastal habitats caused by oil transshipment activities.

Oil spills from tankers are a possible threat both to coastal and pelagic habitats. Also, groundings or collisions of tankers and other petroleum industry vessels may physically damage reefs, perhaps more so than other vessels because of their sheer size (see Section 2.2.3). The oil and gas industry should take necessary preventive measures (e.g. double hulled tankers). Oil spill response teams should be identified for all likely areas.

2.2.9 Identify other threats to marine habitat and take appropriate actions.

Such threats to sea turtle habitat that do not fit in the previous sections or new threats must be considered and addressed.

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