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Giant trevally spawning aggregation highlights importance of community fisheries management no-take zone

Authors:
OCEANARIUM
Giant trevally spawning aggregation highlights importance
of community fisheries management no-take zone
I. Marques da Silva &T. Hempson &N. E. Hussey
Received: 10 February 2014 /Revised: 26 April 2014 /Accepted: 28 April 2014
#Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2014
Location and timing of spawning aggregations for large tele-
ost predators either remain elusive or constitute core-fishing
sites in developing countries, limiting or confounding man-
agement actions for sustainable harvesting. In the Quirimbas
Archipelago in northern Mozambique, limited artisanal fish-
eries catch data are available, and only emerging management
plans are in place in scattered isolated locations. Artisanal
fisheries, however, are the dominant fisheries sector in the
region, employing a large proportion of the local population
and contributing the main food source for consumption. Giant
trevally (Caranx ignobilis) is a highly valued fish and con-
sumed locally but data on giant trevally spawning locations is
limited (Westernhagen 1974). This is a concern, given
spawning aggregations are extremely susceptible to over fish-
ing, but their functional role is imperative for maintaining
ecosystem resilience. Within a community declared no-take
zone on the eastern point of Vamizi island, a large aggregation
of giant trevally were observed by scuba divers on December
15, 2013, two days prior to the full moon. The fish entered the
shelf edge at 1520 m depth from the adjacent deep-water
reef channel during daylight hours (15:00) and two hours after
high tide. The aggregation numbered >1,000 fish that were
estimated to be approximately 80100 cm total length and
larger (Fig. 1a). Individuals were observed pair chasing and
displaying color changes (silver to black; Fig. 1b). The fish
remained in aggregation formation on the shelf for 12min
surrounding the divers before returning to the deep-water
channel. Although the physical release of gametes was not
observed, indirect evidence commonly used to infer spawning
activity, indicate these fish were in the process of spawning
Fig. 1 a Spawning aggregation of >1,000 Caranx ignobilis at the eastern
point of Vamizi Island; diver of 180 cm height on right hand side provides
scale. bIndividual fish coloration changes occurring within the school
I. M. da Silva
Lurio University, Pemba, Mozambique
T. He mp so n
James Cook University, Townsville City, Australia
N. E. Hussey (*)
University of WindsorGLIER, Windsor, Canada
e-mail: nehussey@uwindsor.ca
Mar Biodiv
DOI 10.1007/s12526-014-0235-2
(Domeier and Colin 1997). Primarily, these lines of evidence
are (i) the occurrence of a large number of giant trevally in
aggregation formation at this one site, (ii) the occurrence of
the aggregation by a deep-water channel around the full moon
and (iii) observed courtship behaviors including fish chasing
and coloration changes (Westernhagen 1974; Meyer et al.
2007). This represents the first identified spawning location
for giant trevally in the Western Indian Ocean. Establishing
the occurrence of a vital process such as the spawning location
of a large valuable teleost predator reinforce the no take
designation at this site (Meyer et al. 2007) and highlights the
importance of developing community co-fisheries manage-
ment programs for protecting such processes (Hamilton
et al. 2011). This is particularly important for giant trevally
because spawning locations are considered to be highly pre-
dictable due to their stable occurrence over space and time
(Meyer et al. 2007). Effective management of marine re-
sources in remote and fragmented areas such as the
Quirimbas archipelago are dependent on community buy in
and support through co-fisheries management schemes. This
finding underscores the utility of community-based programs
to protect critical ecosystem functions but highlights the need
for investment in both community and national marine
protected area and fisheries management networks off the east
coast of Africa to ensure an ecosystem based management
approach.
Acknowledgments This finding was documented as part of the Vamizi
Island Fish Telemetry program funded by the World Wildlife Fund. We
thank Ryan Pape for providing the photographs.
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... Identification of novel aggregations is therefore critical for regional conservation of this ecologically, economically, and culturally valuable species. the presence of color morphs associated with both sexes (Panel B, white arrows; Talbot and Williams 1956, von Westernhagen 1974, Meyer et al. 2007), (4) the locations of the aggregations in proximity to deep water (von Westernhagen 1974, da Silva et al. 2015, Daly et al. 2019, see Karnauskas et al. 2011, and (5) the timing of the aggregations, aligning with the warming trend of early summer (Sudekum et al. 1991, Meyer et al. 2007, da Silva et al. 2015, Lédée et al. 2015, Daly et al. 2018, 2019. These observations represent first records of putative C. ignobilis spawning aggregations in the Red Sea, and the count of >800 individuals in Saudi Arabia is the third highest reported in the literature for the species (see da Silva et al. 2015, Daly et al. 2018. ...
... Identification of novel aggregations is therefore critical for regional conservation of this ecologically, economically, and culturally valuable species. the presence of color morphs associated with both sexes (Panel B, white arrows; Talbot and Williams 1956, von Westernhagen 1974, Meyer et al. 2007), (4) the locations of the aggregations in proximity to deep water (von Westernhagen 1974, da Silva et al. 2015, Daly et al. 2019, see Karnauskas et al. 2011, and (5) the timing of the aggregations, aligning with the warming trend of early summer (Sudekum et al. 1991, Meyer et al. 2007, da Silva et al. 2015, Lédée et al. 2015, Daly et al. 2018, 2019. These observations represent first records of putative C. ignobilis spawning aggregations in the Red Sea, and the count of >800 individuals in Saudi Arabia is the third highest reported in the literature for the species (see da Silva et al. 2015, Daly et al. 2018. ...
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