Ms Hayley Nessia1, Dr Diana LaScala-Gruenewald1,3, Dr Hugh Pederson2, Dr Craig Radford1, Dr Nicholas Shears1
1Institute of Marine Science, University of Auckland, Leigh, , New Zealand, 2Innovasea, Hobart, , Australia, 3Monterey Bay Aquarium Research Institute, Moss Landing, , USA
Rock lobster Jasus edwardsii are important predators on rocky reefs in northern New Zealand, but their populations within marine reserves have declined over the last two decades. It is thought to be due in part to lobster being caught on the offshore boundary when they move beyond reefs onto sandy habitats. To better understand the movement of rock lobster within and across reserve boundaries, an array of 47 passive acoustic receivers was installed within the Leigh marine reserve and 51 lobster were tracked over 1.5 years. Due to complex reef topography and low detection rates of lobster, positions were estimated using weighted positioning allowing broad-scale assessment of whether lobster were on reef, reef edge or sand, and rates of hourly detections were used to assess diurnal and seasonal activity. All but 3 tagged lobsters remained within 1 km of their tagged locations and lobster were predominantly found on reef or reef edge (87% of all detections). While there was evidence of some movement onto deeper sandflats, only one lobster was detected beyond the offshore boundary. These results contrast earlier studies which reported large offshore movements and may reflect the considerably smaller population size now present in the marine reserve. While the complexity of rocky reefs reduced signal transmissions and the resolution of movement data, the passive acoustic array still provided evidence of large-scale movement and activity patterns that can inform future management and design of marine reserves.
Presentation Slides – Hayley Nessia
Biography:
Hayley Nessia is a PhD candidate at the Institute of Marine Science at the University of Auckland. Her thesis is focused on spiny lobster (Jasus edwardsii) movement ecology, population status, and potential use as a tool for urchin barren control. She completed her Masters in 2018 investigating invasion biology of the Japanese mantis shrimp (Oratosquilla oratoria) in New Zealand). She has previously worked in terrestrial ecology, investigating impacts of invasive plant species, and also flies a Unmanned Aerial Vehicle (UAV) for the Maui63 charity to search for Maui dolphins.
