Length based specimens

New for 2011

Anglers are increasingly conservation orientated and submissions have been received by the ISFC from anglers and others in recent years regarding the desirability of using length as a proxy for weight. This would allow fish (particularly elasmobranchs) to be returned alive to the water without the requirement for measuring weight on land as is required under the existing ISFC rules. The ISFC undertook to examine the possibility of a “Conservation Specimen” category in 2009, for two species Tope and Blue Shark, which would be based on fish length. A length-based  specimen award is proposed on a pilot basis for Tope for 2011. The threshold length is 1.6 m or 160 cm.

Watch this video for a demonstartion of measuring the length of a shark; put shark on board and measure from tip of nose to folded down tail on board.

Claims will be made on the existing claim form and the angler will specify that length only is being measured. On board weighing of fish is not acceptable (except where a certified motion compensated balance is used). All length data to be given as total length; this is the measurement most often used as an independent variable and is the standard measurement in scientific shark literature (e.g. Campagno, 1984). The fish has to be placed belly down on the measuring device with its dorsal caudal lobe depressed into line with its body axis and total length measured as a point to point distance (not over the curve of the body) from the snout tip to the tip of the dorsal caudal lobe. The snout tip must be placed against a perpendicular front bar or plate to index the 0 cm measurement accurately.

The following evidence must accompany each length-based specimen claim:

1. Photograph(s) showing fish placed belly down on properly extended measuring device with snout against perpendicular bar or plate with the actual recorded length (cm) visible and
2. the sex of the fish. Males can be identified by their claspers (modified pelvic fins) which are thin elongated paired fins situated behind the pelvic fins. Females do not have claspers but have an opening between the pelvic fins.

Permanent attachment of a durable, accurate measuring device to the deck of a boat is one preferred means of providing an accurate measurement. High quality, self adhesive measuring tapes are available from various retailers. Alternatively, a durable roll up device (190 cm in length) has just been launched by IGFA – see http://store.igfa.org/Products/360-official-igfa-measuring-device.aspx for details.

Lengths (cm) as submitted on each claim form were presented in the 2010 report for the first time in 2009. Lengths should be recorded on all claims submitted. Significant length variation is evident for most species. This is due to natural variability (time of year, sex, location, feeding etc) but it is likely that fish length measurement techniques were inconsistent also.

The ISFC requests that all specimen fish are measured according to table below: