Study reveals what seals eat in Tasman Bay
Media contacts:
Andrew Baxter, DOC Nelson/Marlborough marine ecologist, phone: +64 3 546 3172
Trish Grant, DOC Nelson/Marlborough communications advisor, phone +64 3 546 3146
Date: 04 August 2008
A new study gives useful insight into what seals eat in Tasman Bay - primarily anchovy, pilchard, jack mackerel and squid.
The study into the diet of seals at Tonga Island, off Abel Tasman National Park, analysed fish and squid remains in 133 seal faeces samples, known as scats, and 15 regurgitations collected in winter and spring last year (2007). The study was carried out by the National Institute of Water and Atmospheric Research (NIWA) for the Department of Conservation.
DOC Nelson/Marlborough marine ecologist Andrew Baxter said the study aimed to find out what interaction seals had with fish and other marine species in Tonga Island Marine Reserve.
"Some people expressed concern when Tonga Island Marine Reserve was established that the seals would eat all the fish in the reserve but that hasn't happened.
"Blue moki and especially blue cod have increased in abundance and size since Tonga Island Marine Reserve was established in 1993 despite there being a significant and expanding seal colony right in the middle of the reserve. The seals are part of the reserve's marine environment and its natural balance of life.
"The study findings show similarities with studies into seal diet elsewhere in New Zealand that have found seals prefer a diet of squid and oily fish species in coastal areas. These studies show seals are not eating species sought after by recreational fishers as is often suggested."
Mr Baxter said studies at other New Zealand locations had also found deeper water, offshore species including hoki and particularly lantern fish in the seal diet but these were not found in the Tonga Island samples. This was probably due to Tonga Island being so far from suitable deep water habitat and the study taking place at a time when the seals tended to take shorter foraging trips.