General Fisheries Commission for the Mediterranean

Scientific Advisory Committee

sub-committee
on
environment and marine ecosystems

Third meeting

Barcelona the 4-9th of May 2002

MEDLEM PROGRAM

Mediterranean Large Elasmobranchs Monitoring

Subproject Basking shark

IMEDEA

MEDLEM PROGRAM

(Mediterranean Large Elasmobranchs Monitoring)

Subproject Basking shark

The Basking shark (Cetorhinusmaximus) is not a target of any Mediterranean fisheries while this happened in other colder marine regions, where this species has been widely exploited for a long time (U. K., Western Ireland and Norway). In addition to the few sightings made in the open sea, the presence of this shark is mainly evidenced by incidental catches in the trammel nets or in other artisanal fisheries which are frequently used along coastal waters of Mediterranean countries. The Basking shark is the largest Elasmobranch in the Mediterranean Sea and with the giant devilray (Mobula mobular) are the only filter feeders among the cartilaginous fish living in the region. The presence of this species in the Mediterranean region (especially in the north-western part) can be considered frequent mainly in spring and early summer, while sightings during the winter period are rare (Serena et al., 1999).

The Basking shark is probably one of the species that most requires measures of protection, considering its reproductive strategy. In fact it has been included in the Annex II (Endangered or Threatened Species) of the Barcelona Convention for the Protection of the Mediterranean Sea (1976), in the Protocol Concerning Specially Protected Areas and Biological Diversity in the Mediterranean, and signed in Barcelona on 10 June 1995. Moreover, the Mediterranean Basking shark population was added to Appendix II (strictly protected species) of the Bern Convention on the conservation of European Wildlife and Natural Habitats in December 1997.

In order to contribute to the knowledge and conservation of this shark it is important to establish a common procedure to collect data about the specimens that can be accidentally captured or about sightings and stranding in Mediterranean Basin.

In the following sheets we propose a common protocol to collect field dates, to take samples and how to collect them and to measure the different body part of the basking sharks.

We invite all the interested researchers to suggest modification to the present sheets and to put their institute logo in the front page of the document.

Fabrizio Serena and Marino Vacchi

MEDLEM PROGRAM

Data collection field sheet

Accidental capture

Date of capture ______Time of the day ______Depth ______

Latitude ______Longitude ______

Type of Gear ______

Name of the boat ______

Disembark port ______

Leaving animal released Dead animal released Dead animal landed 

Weight ______Length ______Sex ______Photos YES  NO

Sighting/Stranding

Date ______Time of the day ______Depth ______

Latitude ______Longitude ______

Locality ______Town ______Department ______

Number of animals ______Direction ______

How long is the observation? ______Meteo/Sea state ______

Animal: leaving dead putrefy extremely putrefy body parts 

Others information

Stomach contents YES  NO 

Embryo in the uterusYES  NO 

(if possible conserve them freezed)

What kind of samples have you taken? ______

______

Is the animal feeding itself? (gill slits completely open!)YES  NO 

PhotosYES  NO VideoYES  NO 

NOTES ______
______

OBSERVER

Name ______

Complete adress (telephon, e-mail) ______

______

______

Important samples to take and how to conserve them
Alcool 70% / Formalin 4% / Freezed / Bouin
Stomach contents / *** / * / *
Intestine contents / *** / * / *
Gonads / ***
Muscle / *** / *
Liver / ***
Gill and gill-rakers1 / ***
Eye / ***
Vertebra / ***
Skin / ***
Underkin fat / ***
Spermatophores / ***
Parasite / *** / ***
Utera / ***

***Recommended method*Alternative method

1: for the conservation of gills and gill-rakers it will be better to fiss the sample with formalin 10% (formalin and sea water) for a periord of 12-24 h; then rinse the sample with fresh water and store it in alcool 80°.

Technical Terms and Measurements

TOT = total lenghth (snout-posterior tip of the caudal fin)

FOR = fork length (snout-caudal posterior notch)

PRC = precaudal length (snout-precaudal pit, upper origin)

PD2 = pre-second dorsal length (snout-origin second dorsal fin)

PD1 = pre-first dorsal length (snout-origin first dorsal fin)

HDL = head length (snout-5th gill openings)

PBL = prebranchial length (snout-1st gill openings)

POB = preorbital length (snout-anterior eye marging)

PP1 = prepectoral length (snout-origin of the pectoral fin)

PP2 = prepelvic length (snout-origin pelvic fin)

PAL = preanal length (snout-origin anal fin)

Head

EYL = eye length

EYH = eye height

POR = preoral length (snout-mouth)

PRN = prenarial length (snout-nostril)

ING = intergill length (1st-5th gill)

Pectoral fin

P1A = pectoral anterior margin (origin-apex)

P1L = pectoral length (origin-free rear tip)

P1P = pectoral posterior margin (apex-free rear tip)

P1H = pectoral height (apex-insertion)

P1B = pectoral base (origin-insertion)

P1l = pectoral inner margin (insertion-free rear tip)

Dorsal fin

D1A = first dorsal anterior margin (origin-apex)

D1B = first dorsal base (origin-insertion)

D1L = first dorsal length (origin-free rear tip)

D1l = first dorsal inner margin (insertion-free rear tip)

D1P = first dorsal posterior margin (free rear tip-apex)

D1H = first dorsal height (apex-middle point of the base)

1

Caudal fin

CDM = dorsal caudal margin (posterior margin of upper origin

of precaudal pit-posterior tip)

CTR = terminal caudal margin

CST = subterminal caudal margin

CPU = upper postventral caudal margin (subterminal notch-posterior notch)

CPL = lower postventral caudal margin (posterior notch-ventral tip)

CPV = preventral caudal margin (ventral tip-posterior margin

of lower origin of precaudal pit)

Clasper

CLI = clasper inner length

CLO = clasper outer length