Assessing the general health of fish populations, can be investigated using two general methods fishery-independent sampling (e.g SCUBA fish counts or research fishing) and fishery-dependent sampling (e.g. on-board fishery observers or on-shore landing surveys. Fishery-dependent sampling, refers to the direct sampling of fishing activities and catches, generally via fisheries observers aboard fishing vessels or by surveying fishing vessel catches at landing locations (i.e. beach, dock or boat ramp). CTC uses landing location surveys to conduct fisheries status assessment, which utilises a semi-structured interview of fishermen to determine catch type, size and quantity as well as time spent fishing (effort) to estimate the standard fisheries assessment metric Catch Per Unit Effort (CPUE). The interviews also aim to determine the fishermen perspectives as to state of local fisheries, and any perceived changes in changes in catch relative to historic rates.
Data recorded by fisheries catch surveys aim to collect the following information:
- Catch rates
- Target species
- Types of gear used
- Duration of fishing activities
- General locations of fishing activities
- Frequency of fishing activities
- Number of boats fishing
- Number of fishers per boat
- Level of experience of fishermen
- Fishermen perception of changes in local fisheries through time
Although SCUBA fish surveys are common, collect good data and are FUN, they can be resource, time and money intensive. Baited Remote Underwater Video Stations (BRUVS) are a method of sampling fish populations remotely i.e. without entering the water, thereby reducing many of the costs and logistical difficulties of SCUBA surveys. BRUVS use bait, most commonly sardines, to attract fish which are then recorded by a video camera. The primary advantage of BRUVS over more traditional fish survey techniques such as visual census (i.e. SCUBA surveys) is that they can attract cryptic animals or species usually too shy to emerge around divers, which are often overlooked in traditional SCUBA surveys.