Development and evaluation of standardized monitoring and data acquisition systems for the management of mollusc culture in Atlantic Canada

Description

In 2002, the Shellfish Monitoring Network (SMN) in the southern Gulf of St. Lawrence was initiated by DFO in collaboration with the PEI Aquaculture Alliance and the Atlantic Veterinary College. The objective of this study is to develop a standardized system for monitoring shellfish productivity in culture bays. The SMN is based on the European "REMORA" monitoring network.

The protocol is simple, allowing for coverage of a large geographic area, and promoting long term viability of the network. In early spring, juvenile oysters and mussels are deployed at fixed stations throughout the Southern Gulf. Shell growth and meat content are then monitored until late autumn. At each site the animals are kept in a cage and vexar bag, positioned either on the bottom (oysters) or in the water column (mussels). Cages are deployed at locations were food supply and water flow are less likely to be influenced by farming operations, as the object is to monitor growth patterns that reflect the natural changes in the bay environment. This requires multiple cages in some bays with suspected inequities in growing conditions.

In 2002-2003 approximately 60 sites were monitored, the majority of these being located on PEI. Average shell growth rates in 2003 ranged from 0.8 to 3.3 mm/month for mussels and 0.7 to 3.8 mm/month for oysters.

In addition to the monitoring of caged animals, scuba diving surveys were conducted in multiple bays. The objective of these surveys is to measure and document husbandry practices, to see how they correlated with shellfish productivity. In 2003, a total of 59 sites were randomly chosen in 16 bays across PEI. Focusing on the 1-yr old crop, divers measured line spacing, distance between socks. Table 1 shows that the measurements differed noticeably from bay to bay.

Table 1: Results from SCUBA survey. Average sock lengths, distance between longlines (m), distance between socks (m) and sock yield (kg/sock) of all 16 bays surveyed.

Bay #	Average Sock Length (m)	Average Distance Between Lines (m)	Average Distance Between Socks (m)	Average Sock Weight (kg)
1	2.12	20.82	0.37	10.34
2	1.85	15.72	0.37	8.27
3	2.18	18.15	0.42	10.31
4	2.08	12.01	0.47	6.31
5	1.85	6.96	0.38	6.66
6	2.28	9.19	0.40	6.85
7	1.61	9.24	0.44	12.72
8	2.08	13.01	0.45	8.39
9	2.07	6.09	0.58	7.34
10	1.86	8.74	0.51	4.03
11	1.69	11.40	0.37	8.37
12	1.41	8.43	0.37	5.93
13	1.98	9.54	0.37	10.84
14	2.06	10.83	0.57	5.32
15	1.92	16.33	0.46	8.58
16	1.75	13.13	0.43	9.51
Average of All Bays	1.92	11.85	0.43	8.11

The results of both the SMN along with the SCUBA diving survey data will be made available to the growers via a web site which will be updated as new data is obtained. It is hoped that the project will lead to a better understanding of the factors controlling shellfish productivity in an aquaculture setting.

This web site will allow growers to compare the performance of their own lease with other areas to help make more informed decisions about the way they manage there aquaculture sites for increased productivity.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)

Year(s)

2001 - 2005

Ecoregion(s)

Atlantic: Gulf of Maine, Scotian Shelf

Principal Investigator(s)

Luc Comeau
Email: Luc.Comeau@dfo-mpo.gc.ca