As sizes of popular recreational fish increase at Wellington marine reserves we can also expect to see changes in behaviour and habitat for certain species.
Victoria University PhD candidate Tyler Eddy has studied Kapiti and Taputeranga marine reserves and noted increases of the average size of butterfish, red moki and blue cod at Kapiti. The biomass (total mass) of butterfish has increased 10-fold in the last decade at one of the Kapiti sites studied, where he has also observed that this popular species is acting out of character.
“Butterfish are usually quite skittish and cryptic, but in Kapiti Marine Reserve they are definitely more relaxed than those outside the area.
"They tend to occupy the open water unlike those in the fished areas. We could see the same sort of result with other species, such as rock lobster, at Taputeranga Marine Reserve.” says Mr Eddy.
There were as many as five times the number of rock lobsters (commonly known as crayfish) on Wellington’s south coast in the 1950s, and anecdotal evidence suggests they occupied shallow waters. These ‘keystone’ predators have recovered well in other marine reserves, such as Leigh in Auckland, and it’s expected that as lobster biomass increases at Taputeranga Marine Reserve we could see them occupying the intertidal zone.
“Given the level of protection at Taputeranga Marine Reserve, it is likely that lobster numbers will increase, meaning there'll be less invertebrate food sources to go around. As a consequence we may see them venturing closer to shore to enjoy a new vegetarian diet of algae,” says Mr Eddy.
Kapiti and Taputeranga marine reserves are managed by the Department of Conservation which enforces no taking of marine life, including fish and shellfish under the Marine Reserves Act. Popular fish species have been steadily on the rise at the Kapiti reserve since its establishment in 1992. At Taputeranga reserve, on Wellington’s south coast (established in 2008), it is expected that there will be noticeable increases in fish after about three years.
The public can meet marine biologists, learn about their research and explore the touch tanks at an Open Day at Victoria University Coastal Ecology Lab on 5 March, as part of Seaweek.
Seaweek 2011 runs from 26th February to 6th March and the theme is Back to the Future - history, culture and traditions of the sea. Kia kaha tangata moana.