Fisheries Flashcards
What does the survival rate of fisheries captures depend on?
- Environmental conditions
- Availability of veterinary care
- Presence and density of potential predators in the area
What are the immediate impacts that fishery interactions can have on sea turtles?
- Physical injury
- Forced submergence/drowning
- Clinical effects
- Decompression sickness
What are some of the long term effects that fishery interactions can have on sea turtles?
- Immunosuppression
- Reduced growth rates
- Reproductive output
What are the different types of interactions that sea turtles can have with fisheries?
- Entrapment: restricted space but free swimming (ex: pond nets)
- Entanglement (ex: gill nets, trawls, pot/trap lines, hook and line)
- Forced submergence (ex: gill nets, trawls, pot/trap lines, longlines)
- Exertion of evasion and excluder transit (ex: trawls)
- Direct trauma (ex: scallop dredges)
Describe trawls and how sea turtles interact with this type of gear
- Active fishing gear
- Results in entanglement
- Nets = dragged or pushed by vessels to capture various types of marine life
- Sea turtles will typically interact with trawls while foraging or resting at the bottom of the ocean floor resulting in drowning, asphyxia, and the bends
Describe gillnets and how sea turtles interact with this type of gear
- Passive fishing gear
- Large rectangular mesh nets secured to the bottom, mid-water, or near the surface
- Sea turtles may be attracted to fish caught in gillnets resulting in entanglement
Describe pound nets and how sea turtles interact with this type of gear
- Fixed fishing gear
- Uncovered nets allow for entangled sea turtles to breath
- Covered nets are a major drowning risk
- Lower mortality rate compared to other gear types
Describe pots and traps and how sea turtles interact with this type of gear
- Most frequent interaction seen on Long Island
- Lobster, crab pots, and fish traps rest on the ocean floor and are connected to the surface with vertical lines
- Entanglement in vertical lines = a major issue
Describe fishing dredges and how sea turtles interact with this type of gear
- Dredges = towed along the sea floor to scoop up benthic invertebrates
- Sea turtles can be captured and severely injured, have trauma of the carapace, limbs, or skull, or drown
Describe longlines and how sea turtles interact with this type of gear
- Main line with hooks attached along its length
- Sea turtles attempting to eat bait can either swallow the hook or get hooked
- Can result in entanglement
Describe recreational fishing and how sea turtles interact with this type of gear
- Fishing of aquatic animals that do not constitute the individuals primary resource to meet basic nutritional needs
- Sea turtles can become entangled in fishing line, ingest fishing hooks, or get hooked
What are some of the physical injuries that sea turtles can experience as a result of recreational fishing hooks?
The majority of injuries are caused by ingestion which can lead to…
- Abscess formation
- Impaired swallowing
- Septicemia
- Impairment of feeding behavior or jaw movement
The severity of trauma depends on the location and the force of traction applied to the line during capture
What is the treatment protocol for sea turtles that have ingested
- Recently lodged hooks may be ok to leave (why?)
- Dehooking devices
- Surgery
Treatment will vary based on the size and behavior of the animal, location of the look etc
Describe vessel strikes
A collision between any type of boat and a marine animal
This s one of the most common reasons for a sea turtle to be admitted to rehab
What is the treatment protocol for sea turtles that have injuries due to vessel strike?
- Euthanasia
- Dry docking
- Topical treatment (manuka honey)
- Shell fracture fixation (stabilization using bone plate or orthopedic wires)
The severity of the situation must be taken into consideration
What physical injuries can sea turtles experience due to entanglement?
- Drowning
- Low blood supply to flippers
- Reduced air supply
- Mild edema
Line attached to hook = most dangerous
How are in water entanglements conducted?
- Typically conducted for leatherbacks on a vessel
- Takes multiple people
- Turtle will not be admitted for rehabilitation following gear removal
- You want to make as few cuts as possible to allow you to disentangle the animal AND identify the gear type
What is the treatment protocol for entanglements in lines and nets?
- Rehab (6-9 months)
- Removal of gear (allows for blood supply to return to area of injury)
- Antibiotics
- Topical care
Describe decompression sickness (DCS) in sea turtles
- The bends
- Nitrogen-rich bubble form in the cardiovascular system and other issues
- Experienced by turtles that = caught i trawls and gillnets at a depth greater than 10m
What other factors other than depth are factors that can contribute to the bends?
- Duration of submergence and flight response to capture
Why is it hard to diagnose/treat the bends in sea turtles?
- Symptoms can take several hours to develop
- There is no “reasonable” treatment for DCS (effective treatments must occur immediately and consist of a hyperbaric chamber, IV fluids, steroids, antibiotics etc.)
- When DCS is observed it is typically after a turtle is caught in a fishing net on a vessel out on the open ocean, even if there is a biologist/vet on board there are very little resources that can be used to rehabilitate the turtle on sight. The vessel is also often too far from shore to get the animal care in enough time.
What are some bycatch reduction strategies?
- Turtle excluder devices (TEDs)
- Enforcement of fishing restrictions
- Promoting awareness
Describe turtle excluder devices and how they mitigate bycatch
- Allow for captured turtles to escape trawl nets
- Developed in 1980 through a collaboration between National Marine Fisheries Service (NMFS) and commercial shrimpers
- Mandated seasonally in the US shrimp otter trawl fishery in 1987
- TEDs became required in otter trawls year round 1994
What are some restrictions that can be enforced to help mitigate sea turtle bycatch?
- Decreasing tow time duration
- Towing at night when there is less turtle activity
- Establishing time and area closures along migratory routes, nesting zones, foraging areas and other hotspots
