Feeding behaviour of some marine mammals on occasion results in some animals being caught in trawl nets. Industry driven operational procedures now require all vessels to adopt fishing strategies, which will, to the best of their abilities, minimise interactions with marine mammals. Every effort is made to ensure any marine mammals caught in nets are released alive and unharmed.

Sea Lions

The New Zealand sea lion is a rare species of sea lion and is listed as "nationally critical" by the Department of Conservation after a decline in pup numbers at the breeding colonies in the Auckland Islands. It was reduced to very low numbers by hunting and harvesting for skins (prior to 1900). Since that time the populations on the Auckland Islands and Campbell Islands in the Sub-Antarctic have increased and appear stable. Some sea lions live, and are slowly starting to breed, on the mainland, particularly Otago.

The New Zealand sea lion (Phocarctos hookeri) forages in the same range as the Auckland Islands squid trawl fishery. The fishery occurs during summer and autumn every year when sea lions are concentrated in their breeding areas on the Auckland Islands.

While not dependent on squid (sea lions eat a wide range od fish, cephalopods and crustaceans) sea lions are known to feed on squid from trawls and are encountered during trawling.

Every year a number of sea lions are drowned as a result of being captured in trawls during fishing. As a result of these interactions the fishery is closely monitored and managed by the Ministry of Fisheries to ensure that the incidental mortality level does not effect the sea lion population's overall integrity.

The seafood industry is working in collaboration with the Ministry of Fisheries and Department Of Conservation to minimise all interactions between marine mammals and harvesting practices.

One such initiative is the development of a Sea Lion Exclusion Device (SLED) within the net. This normally consists of a strong grid placed at an angle across the front of the opening of the net. The grids are big enough to let squid swim through but are too small for larger creatures, such as sea lions to get through. They are guided up the grid, by the motion of the water and can then escape by swimming through an opening in the top of the net.

The SLED mitigation device has been in use since 2000 and are continually improved and modified to maximise their effectiveness in minimising captures of sea lions.

Sea lion population dynamics and interaction with harvesting operations is closely measured and analysed by the Ministry of Fisheries and DoC, working collaboratively with the seafood industry in a comprehensive fishery observer program. The seafood industry pays hundreds of thousands of dollars each year to facilitate Ministry observers on-board fishing vessels in the most highly observed fishery (38% of all trawls in the SQU6T area in 2009) in the New Zealand EEZ.

In 1986 a 12 mile nautical mile 'no trawl' zone around the Auckland Islands was established under the Fisheries Act to protect the sea lion specifically from incidental trawl captures. In 2003 total protection to marine biodiversity in the territorial sea around the Auckland Islands was guaranteed by the formation of a full marine reserve.

Fur Seals

The New Zealand fur seal (Arctocephalus forsterii) frequents most New Zealand waters and is also found in some Australian seas. While harvested in the mid 18th century to very low levels for their skins, New Zealand fur seal populations around New Zealand are growing under their protected status.

Fur seals are renowned for becoming involved in fishing operations (as are seabirds) due to the ease with which they can forage food from the vessel's catch.

Reducing interactions with species who are determined to be involved in "sharing the catch" is always difficult, made more so becuase fur seals are smart and aggressive.

Dolphins

The New Zealand common dolphin (Delphinus delphis) is found in waters around the world including those of New Zealand. The Department of Conservation (DoC) note that in New Zealand, this species tends to remain a few kilometres from the coast and is particularly common in the Hauraki Gulf and off Northland.

 

Mitigation

The Deepwater Group Ltd has been active in the development and adaptation of the Marine Mammal Operation Procedures (MMOP) intiative introduced tot he New Zealand seafood harvesting sector. The purpose of the MMOP is to reduce the risk of incidental captures of marine mammals during deepwater fishing operations in New Zealand's exclusive economic zone (EEZ).

The MMOP applies to all trawlers over 28m in length fishing in New Zealand's EEZ and to all protected marine mammal species encountered during fisheries operations including sea lions, fur seals and dolphins.

Below is a copy of the current MMOP.