Assessment of the fishery of siganid juveniles caught by bagnet in Lagonoy Gulf, Southeastern Luzon, Philippines

Abstract

Summary Long‐term, excessive harvesting of juvenile fish could lead to significant decline in their settlement strength. In the Philippines, the exploitation of siganid juveniles forms an important traditional fishery but no assessment of the exploitation status of such fishery had been made. The present study is a comprehensive assessment of the siganid juvenile fishery caught by bagnet in Lagonoy Gulf (Southeastern Luzon) by analyzing the temporal trend of their catch and effort statistics. Seven species of siganid juveniles composed the catch, which was dominated by Siganus canaliculatus (78%), S. spinus (8%) and S. argenteus (3%). Total catch 2001 through 2004 was 175 tonnes (t), 154 t, 130 t and 65 t, respectively. The total catch as well as the catch‐per‐unit‐effort declined steeply in these 4 years. Juvenile occurrences or ‘runs’ were observed throughout the year except in some months in the later quarters of 2003 and 2004. Catches for all 4 years were always highest in April and May, occurring on or about the new moon mostly at the Albay East Coast. Overfishing must be stopped in order to prevent the collapse of this resource.

The application of genetics to marine management and conservation: examples from the Indo-Pacific

“…Relatively much is known about the biology and ecology of the mottled spinefoot (e.g., Alcala et al 1979, de la Paz and Aragones 1990, Woodland 1990, although some confusion still exists in distinguishing the species from its morphologically similar sibling species, Siganus canaliculatus. Several studies of mottled spinefoot populations in the Philippines have focused on population structure, dynamics, and exploitation status toward rationalizing and proposing management schemes for catch regulation (Soliman and Yamaoka 2010) or establishment of marine reserves (Bellefleur 1997, Jumawan-Nanual andMetillo 2008).…”

Early life-history of the spiny siganid Siganus spinus (Linnaeus 1758) inferred from otolith microstructure

“…Actual observations of the settlement were done by SCUBA diving in the lagoon of the island during the ‘run’ days. A unit of settlement was expressed as a ‘run’ that is the occurrence of juveniles on a given day; the number of ‘runs’ each month was positively correlated with monthly settlement volume (Soliman and Yamaoka, in press).…”

“…The tuna caught by hand‐lines were stored in ice inside styrofoam boxes for laboratory examination 3–4 h after capture. Key distinguishing mark of the spiny siganid was the dark‐brown mottled body, characteristic of the species (Soliman and Yamaoka, in press). The stage of development (i.e.…”

“…Seine net samples were obtained on‐site where juveniles were harvested. Most of these captured juveniles could have been those that escaped bagnets the previous night as well as late‐arriving juveniles (Soliman and Yamaoka, in press). All specimens were preserved in 90% ethanol immediately after collection and brought to the laboratory for examination and otolith extraction.…”

Stable isotope analysis suggests the existence of multiple populations of streaked spinefoot (Siganus javus L.) in Bandon Bay, Southern Thailand

“…Siganus javus is an omnivore, its diet including zooplankton, such as copepods (Yuniar et al 2007), and seaweed (brown microalgae) (Noda et al 2011). In addition, the analyses of otolith microelements in a related species, Siganus fuscescens, have revealed juvenile seasonal population changes (Soliman and Yamaoka 2010); and migration to, and habitation in, river estuaries in its early life stages (Yamada and Baba 2009). A study in Mikawa bay, Japan, indicated that the adult stage of S. fuscescens tends to be inhabiting around the mouth of the bay where close to the open water; however, there was no significant spatial difference in immature stage between two different sites in shoreline (Kamohara et al 2007).…”