Fish Aggregation Database

The list below provides a description of each parameter used in the SCRFA

Parameters used in the SCRFA

Aggregation (Spawning): a grouping of a single species of reef fish that has gathered together in greater densities (i.e. at least three to four times) than normal with the sole purpose of reproducing.

Aggregation duration: The length of time (from hours to months) that the spawning aggregation lasts for.

Area of aggregation: Two-dimensional substrate area over which the aggregation was observed to form at maximum numbers observed.

Catch Per Unit Effort (CPUE) trend: CPUE is a useful way of quantifying the amount of fish caught in relation to the amount of fishing performed; it is a proxy of abundance but much care is needed in its use because of the issue of ‘hyperstability’. Units for CPUE depend of the type of fishing and weight units, e.g. kgs fish per hook per fisher per hour, number fish caught per 50 m length gill net per day. Changes in CPUE over time if applied carefully can sometimes be used to infer changes in the numbers of fish in the spawning aggregation providing certain assumptions are met (see hyperstability consideration).

Current status: Either a quantitative evaluation or a qualitative assessment of expert opinion regarding the current status of the aggregation relative to the past. Categories are: Same (i.e. no change); Increasing; Decreasing, Gone. See Status parameter(s).

Fish numbers: An index to describe the peak (maximum) number of fish observed for a given species in an aggregation at one time.

Habitat: Smaller scale site details such as rubble, sand channels, seagrass.

Management/Protection: This field indicates whether the aggregation is managed or if the aggregating species is protected in any way during the time that the aggregation forms. Examples include a ban on sales during spawning season, Marine Protected Area (no-take), time/area closures, size limits, landing quota, limited entry, none.

Enforcement: The level of enforcement for any management measures i.e. Strictly, Moderately, Lightly, None, Don’t know. Monitoring type

Methodology used to monitor the aggregation: Examples include visual transects, visual point surveys, landings, test fishing, interviews, CPUE, etc.

Monitored by: The affiliation of the person monitoring/reporting on the aggregation, e.g. individual, organization, government department.

Moon phase:The lunar phase (new moon, first quarter, full moon, third quarter) during which aggregations were noted.

Reef geomorphology:The larger scale coral reef type such as Promontory, Drop-off, Reef Crest, Reef Channel, Inner/Outer Reef, or a verbal description.

Resident aggregations: are formed by fish that travel short distances from their home areas or shelters to aggregation sites and assemble on a regular basis, sometimes almost daily, and often over extended periods throughout the year. Transient aggregators are generally small to medium in size. Aggregation formation may be associated with particular lunar phases.

Signs of spawning: To confirm that the aggregation observed has formed for the purpose of spawning, rather than for some other purpose (such as for feeding), both direct and indirect indications can be used.

Direct signs provide unequivocal evidence for spawni including spawning, hydrated eggs, postovulatory follicles.

Indirect signs that fish have gathered to spawn include regular courtship, colour changes observed exclusively in association with reproduction, multiple gravid females in catches or observed, etc.

Status parameter(s): An explanation of the parameters and data used to deduce the current status of the aggregation. Parameters could include data of the following collected over several years: CPUE, numbers of fish, density, extent of aggregation area, average fish size landed. Any changes in fishing practices that could have caused, at least in part, such changes to occur (e.g. changes in gear type used, introduction of fishery management, etc.) are also included, if available.

Tidal movement: Whether the tide was high, low, incoming or outgoing.

Time of spawning: The time of day at which spawning (i.e. egg/sperm release) was observed/occurs in the field. Examples include Sunset, Sunrise, Noon, or Military time.

Traditional (or Local) knowledge details: Information on spawning aggregations that have been exploited for multiple years and are known to the community – maybe across multiple generations. Such information is typically not formally recorded and is particularly prevalent or available from Pacific Island Nations. Often this is the only information available on specific aggregation sites and histories.

Transient aggregations: are typically formed by medium to larger species physically able to travel greater distances, as much as tens or even hundreds of km. However a number of smaller species also mate in transient aggregations. These aggregations usually form for one to multiple months in the year and may last one to several weeks at a time. Aggregation formation may be associated with particular lunar phases

Type of spawning: The type of spawning observed, either pair-spawning (male and female pairs), or group-spawning (a group of fish rise together in the water column, typically comprising a single female and multiple males).

Type of aggregation: An aggregation refers to a group of fish of the same species gathered together, as indicated by fish densities or numbers being significantly higher than those found during the non-reproductive period. Aggregations are classified loosely into TRANSIENT or RESIDENT, but intermediate forms can occur.

Visibility: The maximum horizontal underwater visibility when dive surveys were undertaken.

Year discovered: The year the spawning aggregation was first discovered.

Year first exploited: The year the aggregation was first known to be fished.

Percent of known exploited reef fsh spawning aggregatons determined to be declining, disappeared, stable or increasing globally; the current status of many is unknown

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