References and Protocols
A large number of different monitoring tools are available for use, as part of a comprehensive monitoring plan. The accompanying table is intended to help managers decide which monitoring methods are best suited to fulfill the needs of the site. The table can be sorted by the monitoring method, level of importance, cost, level of expertise needed, or question addressed. Click on the column title to sort the data. More resources are listed below the table.
| Monitoring Method | Relative Importance | Relative Cost | Level of Expertise in Skills Needed | Expertise Needed | Questions Addressed | Description |
| Adaptive bathymetry | medium | $$ | medium | Some expertise to analyze the data and produce maps with specialized mapping software packages | What is the geomorphology of the FSA? | A fish finder is used to map the site and construct a digital elevation model of the FSA. |
| Bathymetric mapping | medium | $$$ | medium | Some expertise to run the equipment and analyze the data with specialized mapping software packages | What is the geomorphology of the FSA? | A GPS, digital depth sounder unit, and laptop computer are used to map the bathymetry of the site. |
| Underwater photomosaic mapping | low | $$$ | medium | Need to acquire underwater imagery and be able to use Photoshop software to mosaic images | What is the nature of the benthic habitat at the spawning site? | An underwater digital camera is used to photograph the site and the photos are patched together to make a site map. |
| Underwater visual census | high | $$-$$$ | medium | SCUBA diving and basic training in UVC | How many fish are at the FSA? | A diver enters the water and counts the number of fish present (only useful for FSAs with small numbers of individuals). |
| Underwater visual census (transects) | high | $-$$ | medium | SCUBA diving and basic training in UVC | How many fish are at the FSA? | Divers count the number of fish across transects of a specified size and use data to extrapolate an estimate of the total number of individuals, based on the total known FSA area and fish density throughout the FSA. |
| Underwater visual census (stationary counts) | high | $-$$ | medium | SCUBA diving and basic training in UVC | How many fish are at the FSA? | Divers count the number of fish in a circular area at stationary survey points and extrapolate to estimate the number of individuals, based on total FSA area; some knowledge of densities within the FSA are needed. |
| Underwater visual census with video camera | high | $$-$$$ | medium | SCUBA diving and basic training in UVC and videography | How many fish are at the FSA? | Divers film the FSA with underwater video cameras and the footage is later used to estimate the number of individuals. |
| Length and weight determination from market samples | medium | $-$$ | low | Ability to identify fish species and measure fish systematically | What is the length and weight distribution of the spawning fish? | Fish taken from the aggregation (either by catch-and-release sampling or from fishers' catches) are measured and weighed. |
| Sampling gonads | medium | $-$$ | medium | Ability to identify gonads | What is the sex distribution of the spawning population? | Fish are caught from the aggregation, sexed non-surgically, and released. |
| Determining fishery-dependent sex ratio | high | $-$$ | low | Ability to identify gonad stages | What is the sex ratio of fish taken from the FSA? | As commercially caught fish are gutted, their gonads can be observed and sex ratios can be determined. |
| Gonadosomatic index | high | $-$$ | low | Ability to measure fish and identify and weigh gonads; basic math skills | What is the seasonality of spawning? | A sample of females is taken over a period of time (e.g., monthly throughout the year) and the gonadosomatic index is calculated to determine spawning season(s). |
| Determination of time of day of spawning | low | $-$$ | medium | Ability to identify stages of egg maturity in females | What is the time of day that spawning occurs? | Females are sampled throughout the time spent at an aggregation and hydrated eggs signal near-spawning time. |
| DNA sampling and analysis | high in some cases | $$-$$$ | high | Expertise in genetic laboratory techniques needed | What is the population structure of the FSA? | Fin clips or other tissues are taken from a large (can be quite small depending on the question) sample of spawning fish, and DNA analyses can show how closely related spawning individuals are |
| Ageing of population using otoliths | high in some cases | $$-$$$ | high | Expertise in preparing and reading otoliths is needed | What is the age structure of the fished population of the FSA? | The otoliths (earbones) of a sample of fish are extracted and used to determine the age of the fish. |
| Using CPUE to measure abundance | low | $ | low | Ability to identify fish species | Are there increases or decreases in CPUE that may indicate changes in abundance? | Catch and effort data from fishermen are used to calculate an index of abundance; should be combined with UVC to understand how catchability changes with changing abundance. |
| Autonomous Underwater Video system | medium | $$$ | high | Expertise in running the AUVS remotely | What are the behavioral and compositional characteristics of the FSA? | A remotely operated video camera can be installed at the area of spawning and the timing and other characteristics of spawning can be observed. |
| Temperature determination | medium | $ | low | None, but need to know details of reproductive seasonality and timing to create linkages | Is spawning correlated with changes in water temperature? | Water temperature is measured over a period of spawning and changes in temperature may be correlated with spawning. |
| Current flow measurement | low | $$$ | low | Expertise in running physical oceanographic equipment | What are the physical conditions at the time of spawning? | Current and other physical parameters are measured over a period of spawning and can be correlated with spawning activity. |
| Tag and release | medium | $$-$$$ | medium | Ability to process live fish, including maintaining health; understanding of tag-release theory | Where do spawning fish migrate to and what is the level of vulnerability? | A sample of fish are tagged and released, and as they are recaptured their locations are reported |
| Acoustic telemetry | medium | $$$ | high | Ability to surgically implant acoustic pingers, download receiver data, and analyze data | What are the movements of spawning fishes? | An acoustic array of receivers is set up around the area of study and spawning fish are surgically implanted with pingers that will be recorded by the acoustic array to determine the location and movement patterns of the fish. |
| Submersibles and ROVs (Remote Operating Vehicles) | low | $$$$ | high | High level of expertise needed to operate equipment | Are fish spawning at depths below the limits of safe diving? Behavior? | ROVs and submarines are used to make direct observations of fish behavior and FSA composition in areas of the marine environment below safe diving limits. |
| Tracking larvae with plankton tows | low | $$$ | high | Expertise in conducting plankton tows and identifying fish larvae | Where are spawned eggs being transported? | Plankton tows can give very precise information on the relative densities of eggs and fish larvae at varying distances away from the FSA. |
| Larval recruitment studies | high | $$$ | high | Expertise in setting light traps or identifying newly-settled larvae on a reef | What is the level of recruitment in the sampled area? | Light traps or direct observation of newly recruited larvae using SCUBA are used to estimate relative success of spawning over time. |
| Documenting the size and nature of the fishery | high | $-$$ | medium | Ability to identify fish species, basic knowledge of the fishery, including locations and methods | What is the nature of the fishery dependent on the FSA? | Direct observation is used to record information on number of boats, fishers, gear, and catch. |
| Market and subsistence catch surveys | high | $-$$ | low | Ability to identify fish species | What is the seasonality of the fishery? | Direct observation of fish markets is used to assess trends in abundance and seasonality of the fishery. |
| Fisher interviews | high | $ | high | Ability to identify fish species; skill in interview techniques | What are the characteristics of the FSA and the fishery? | Interviews with fishers can supply a significant amount of information on the FSA, the fishery, and the health of fish populations. |
Resources
Several sources contain detailed information on these methods, including the following.
- Fish spawning aggregation sites in the MBRS region: recommendations for monitoring and management (Heyman and Requena 2003)
- Case study: mapping Half Moon Caye's reef using the Adaptive Bathymetric System (ABS) (Ecochard et al. 2003) (download pdf, 5,511k)
- Talking to fishermen (SCRFA)
- Manual for the Study and Conservation of Reef Fish Spawning Aggregations (SCRFA)
- Introduction to monitoring of spawning aggregations of three grouper species in the Indo-Pacific: A manual for field practitioners (Pet et al. 2006) (download pdf, 3,812k)
- FSM Spawning Aggregation Monitoring Training Workshop Report, Black Coral Island, Pohnpei, Federated States of Micronesia (Rhodes 2004) (download pdf, 2,550k)
- Reef fish spawning aggregation monitoring protocol for the wider Caribbean (Heyman et al. 2002) (download pdf, 1,424k)
- Protocolo para el monitoreo de agregaciones reproductivas de peces arrecifales en el Arrecife Mesoamericano y el Gran Caribe (Heyman et al. 2002) (download pdf, 1,496k)
- Development of fisheries management tools for trade in humphead wrasse, Cheilinus undulatus, in compliance with Article IV of CITES – Annex II Underwater Visual Census of Cheilinus undulatus (humphead wrasse, Napoleon fish) in three areas of Indonesian waters, 2005 (Sadovy 2006)