NIWA West Coast Estuaries – subtidal fish surveys

West Coast estuaries are surveyed with beam trawls to collect 0+ snapper and using barium and titanium concentrations in otoliths follow the distribution of juveniles along the coast. The secondary aim of the project is to quantify subtidal small fish assemblages. Purpose: To follow the distribution of 0+ snapper and to quantify subtidal small fish assemblages.

Barium and titanium concentrations in 0+ snapper otoliths/tissue. Chemical signature library allows comparison with open coast adult snapper to help identify estuaries of origin, estuary contribution, spread from harbours, and seasonal homing patterns. Small fish distribution and population size within sampled estuaries. Port Waikato, Raglan, Kawhia and Aotea are to be surveyed in May/June 2003.

West Coast estuaries including Port Waikato, Raglan, Kawhia and Aotea.

Beam trawls Otoliths and tissues are run through elemental analysis.

Additional comments: 0+ catch rates are showing the critical importance of all of the West Coast as nursery groups. Related information: NIWA Estuarine fish gradients study – Papakura Channel, Manukau Harbour. This study assesses effects of depth, substrate / secondary habitat methods, season, prey assemblages, and turbidity using multiple sampling methods over a 20 km gradient frommuds to sands (turbid to clear waters). It looks at trophic interactions and annual variability. This study is relevant to other west coast harbours.