A multi-indicator system and the Traffic Light methodology (TL) to provide the first description of the Illex coindetii (Verany 1839) stock in the GFCM geographical sub-area (GSA) 18 (southern Adriatic Sea; Central Mediterranean) were applied using independent fishery data (‘‘Mediterranean Bottom Trawl Survey’’, ‘‘Medits’’, programme, years 1996–2004). The trajectories of nine population indicators of Frequency of Occurrence (F), Biomass (BI), Density (DI), Recruit Strength (RS), Spawner Strength (SS), Mean Body Weight (MBW), Mantle Length (ML), Mantle Length Excluding Recruits fraction (MLER), Mean mantle Length-Females Length at maturity ratio (MLLm), were analysed using statistical estimators as arithmetic and geometric mean, median, and 75th percentile. The TL methodology was applied to analyse the resulting multiple-indicator panel. Results describe a significant trend of the I. coindetii stock (in number) in the GSA 18 related to a shift within its structure due to a greater proportion of small specimens in the population. Factors that may be contributing to the observed changes are sea temperature, the reduction of possible predators, the recovery of some prey species mostly due to the fishing pressure occurring in the area, and the fast growth and short life span of I. coindetii. In a dynamic system like the Adriatic Sea, the capability to respond quickly to the ‘‘environmental’’ or ‘‘ecosystem’’ changes seem to give I. coindetii an advantage in competition with the long lived finfish species. Accordingly, there is potential to use squid population dynamics as recorders to track environmental and ecological changes, as well as overexploitation. The adopted methodology drew attention to changes occurring within the stock of I. coindetii, and could provide an opportunity for managers to consider action at an early stage. The multi-indicator system and the TL methodology are illustrated as means to follow dynamic changes within squid stock, and to provide usefu

A ‘‘Traffic’’ Light approach for the assessment of the Broadtail shortfin squid Illex coindetii Verany, 1839 in the Southern Adriatic Sea (Central Mediterranean

TOTEDA, Francesco
2007-01-01

Abstract

A multi-indicator system and the Traffic Light methodology (TL) to provide the first description of the Illex coindetii (Verany 1839) stock in the GFCM geographical sub-area (GSA) 18 (southern Adriatic Sea; Central Mediterranean) were applied using independent fishery data (‘‘Mediterranean Bottom Trawl Survey’’, ‘‘Medits’’, programme, years 1996–2004). The trajectories of nine population indicators of Frequency of Occurrence (F), Biomass (BI), Density (DI), Recruit Strength (RS), Spawner Strength (SS), Mean Body Weight (MBW), Mantle Length (ML), Mantle Length Excluding Recruits fraction (MLER), Mean mantle Length-Females Length at maturity ratio (MLLm), were analysed using statistical estimators as arithmetic and geometric mean, median, and 75th percentile. The TL methodology was applied to analyse the resulting multiple-indicator panel. Results describe a significant trend of the I. coindetii stock (in number) in the GSA 18 related to a shift within its structure due to a greater proportion of small specimens in the population. Factors that may be contributing to the observed changes are sea temperature, the reduction of possible predators, the recovery of some prey species mostly due to the fishing pressure occurring in the area, and the fast growth and short life span of I. coindetii. In a dynamic system like the Adriatic Sea, the capability to respond quickly to the ‘‘environmental’’ or ‘‘ecosystem’’ changes seem to give I. coindetii an advantage in competition with the long lived finfish species. Accordingly, there is potential to use squid population dynamics as recorders to track environmental and ecological changes, as well as overexploitation. The adopted methodology drew attention to changes occurring within the stock of I. coindetii, and could provide an opportunity for managers to consider action at an early stage. The multi-indicator system and the TL methodology are illustrated as means to follow dynamic changes within squid stock, and to provide usefu
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11586/50182
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 16
  • ???jsp.display-item.citation.isi??? 15
social impact