Project number: 2014-028
Project Status:
Completed
Budget expenditure: $250,432.00
Principal Investigator: Xiaoxu Li
Organisation: SARDI Food Safety and Innovation
Project start/end date: 16 Jul 2014 - 29 Jun 2017
Contact:
FRDC
SPECIES

Need

Mud cockles have been an important resource to the seafood industry, recreational fishers and ecosystem of SA. These species are subject to episodic recruitment that is strongly influenced by the environment. For example, the combination of fishing and adverse environmental conditions at the Section Bank has resulted in PIRSA closing this area to fishing from 2011. As these difficulties could arise in any mud cockle fishery, e.g. a severe mud cockle mortality event occurred during December 2013 in Streaky Bay, there is a strong need to develop the capacity to recover the depleted stocks through reseeding. Section Bank is an ideal location for a case study because it has been closed to commercial and recreational fishing for more than three years.

While marine stock enhancement/restoration programs are variable in success, the approach seems well suited to cockle species, which in many countries are farmed by planting spat into the sandy substrate and harvesting them when they have reached market size. Stock enhancement/restoration also continues to advance with improved policies (e.g. PIRSA F&A Draft Policy for the Release of Aquatic Resources) and the “responsible approach” advocated by Lorenzen et al (2010) and Hart et al (2013) where methodologies are used to ensure that the genetic heterogeneity of natural populations is maintained and that hatchery stock is disease free before release.

Benefit cost analyses have shown very encouraging potential for stock enhancement in pipi and greenlip abalone. For example, a benefit cost ratio of 3.34:1 and a two year investment return were anticipated for pipi reseeding in NSW (Phelps et al 2008). Similar or greater levels of benefit can be predicted for mud cockle stock enhancement in SA by substituting the information for pipi with that for K. rhytiphora based on our findings in FRDC 2009/208 project.

Objectives

1. Develop optimal methodologies for transporting and planting hatchery produced mud cockle, K. scalarina, for stock enhancement/restoration at Section Bank.
2. Evaluate post-stocking performance of two hatchery produced mud cockle, K. scalarina and K. rhytiphora, at Section Bank.
3. Develop a monitoring program that can be incorporated within the existing industry mud cockle stock assessment program to determine the long-term success of stock enhancement/restoration.
4. Optimise mud cockle stock enhancement/restoration strategies for Section Bank through benefit cost evaluation of different options using the model developed in FRDC project 2008/071.
5. Transfer knowledge gained from this project to Government fisheries and aquaculture managers and policy makers, and cockle fishers in SA.

Final report

ISBN: 978-1-876007-38-6
Authors: Miller-Ezzy P.A. Stone D.A.J. and Li X.
Final Report • 2021-08-01 • 1.59 MB
2014-028-DLD.pdf

Summary

This study was conducted to restore the Mud Cockle population in the Section Bank of Port River, South Australia, which had drastically decreased due to commercial fishing. Mud Cockles are important not only for commercial purposes but also for stabilizing sediment and reducing turbidity in the environment. The study developed procedures for transporting and planting hatchery-produced Mud Cockle seed into the field to optimize growth and survival. Pilot studies were undertaken to assess transportation and tagging procedures. Five trials were conducted at two different sites with different population sizes with the aims of testing planted Mud Cockle survival and growth across different seasons, sites, stocking densities, stocking size classes and predator protective methods. The study found that seasonal water temperature has the strongest influence on the apparent survival and growth of the re-seeded Mud Cockle spat. The results from the pilot studies indicated that Pacific Oyster spat transportation methods were suitable for Mud Cockle spat and painting one valve of the Mud Cockles with Rosario Pink paint was the most effective method for marking experimental spat. 
 

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