247
8 Fishery and Biological Implications of Fishing Spawning Aggregations…
larval pulses that result from the large spawning events associated with aggregations
for capture based aquaculture (CBA). Reef-associated fi shes used for CBA include
certain rabbitfi shes, mullets, milkfi sh and groupers for which seasonal fi sheries on
post-settlement phase fi sh target the massive and concentrated numbers of settling
recruits (Lovatelli and Holthus 2008 ) . As one example, over a few months of the year
in many Pacifi c islands the young of several species of rabbitfi sh, barely 2 months
old, regularly recruit as a massive balls of tiny fi sh on shallow seagrass areas, mangroves, reef fl ats or beach areas. They are collected in their millions by push nets, cast
nets, seine nets, and lift nets and grown to market size under captive conditions. They
are so abundant that they have been referred to as ‘endless’ (Teitelbaum et al. 2008 ) .
Over the last two decades, a particularly valuable fi shery for living reef fi sh,
destined for the Chinese seafood market and known as the live reef food fi sh trade
(LRFT), has placed pressure on grouper populations in parts of the Indo-Pacifi c
(Sadovy et al. 2003 ) . The apparently insatiable consumer demand for these fi shes
drives an intensive fi shery to fi ll air and sea consignments on a frequent and regular
basis from many source countries. Aggregations are obvious targets for several of
the preferred species, particularly brown-marbled grouper, camoufl age grouper and
squaretail coralgrouper, that form them, leading to declines in catches in the Solomon
Islands, Papua New Guinea, Palau and the Seychelles (Johannes and Riepen 1995 ,
Hamilton and Matawai 2006 ; Aumeeruddy and Robinson 2006 ) . In Papua New
Guinea (PNG) a Hong-Kong based trial LRFT operation claimed that it was not
economically viable if it could not target aggregations and the operation ceased
when aggregation fi shing was not permitted (Leban Gisawa, PNG fi sheries 2008).
Fiji became involved in the LRFT in the late 1990s but stipulated no fi shing
during spawning or aggregation periods (Ledua Ovasisi, Fiji Fisheries, 2008). Aside
from the large numbers of live fi sh removed from aggregations, which can represent
a high proportion of assembled fi sh, catches of fully ripe females can lead to
signifi cant wastage because gravid fi sh tend to undergo high mortality shortly
after capture.
8.3 Fishery Implications of Fishing Spawning Aggregations
A major challenge is to determine the extent to which exploitation of spawning
aggregations contributes to declines in marine fi sh populations. Few of the 15,500
known marine fi sh species have both the necessary biology and fi shery information
for such detailed assessment. Nonetheless, this task is critically important from a
management perspective, since many of the world’s major fi sheries support or once
supported aggregation-fi shing. The massive landings that once characterized many
highly productive fi sheries involved seasonal gatherings of fi sh at magnitudes far
greater than are seen today (Roberts 2007 ) . Presumably, aggregation-spawning
evolved, for whatever proximate reason, because, ultimately, it resulted in greater
reproductive success compared to a non-aggregating habit. Unfortunately, the very
biological characteristic, aggregation-spawning, that evidently contributes to making such species so productive may also prove to be their ‘Achilles Heel’ when
8 Fishery and Biological Implications of Fishing Spawning Aggregations…
larval pulses that result from the large spawning events associated with aggregations
for capture based aquaculture (CBA). Reef-associated fi shes used for CBA include
certain rabbitfi shes, mullets, milkfi sh and groupers for which seasonal fi sheries on
post-settlement phase fi sh target the massive and concentrated numbers of settling
recruits (Lovatelli and Holthus 2008 ) . As one example, over a few months of the year
in many Pacifi c islands the young of several species of rabbitfi sh, barely 2 months
old, regularly recruit as a massive balls of tiny fi sh on shallow seagrass areas, mangroves, reef fl ats or beach areas. They are collected in their millions by push nets, cast
nets, seine nets, and lift nets and grown to market size under captive conditions. They
are so abundant that they have been referred to as ‘endless’ (Teitelbaum et al. 2008 ) .
Over the last two decades, a particularly valuable fi shery for living reef fi sh,
destined for the Chinese seafood market and known as the live reef food fi sh trade
(LRFT), has placed pressure on grouper populations in parts of the Indo-Pacifi c
(Sadovy et al. 2003 ) . The apparently insatiable consumer demand for these fi shes
drives an intensive fi shery to fi ll air and sea consignments on a frequent and regular
basis from many source countries. Aggregations are obvious targets for several of
the preferred species, particularly brown-marbled grouper, camoufl age grouper and
squaretail coralgrouper, that form them, leading to declines in catches in the Solomon
Islands, Papua New Guinea, Palau and the Seychelles (Johannes and Riepen 1995 ,
Hamilton and Matawai 2006 ; Aumeeruddy and Robinson 2006 ) . In Papua New
Guinea (PNG) a Hong-Kong based trial LRFT operation claimed that it was not
economically viable if it could not target aggregations and the operation ceased
when aggregation fi shing was not permitted (Leban Gisawa, PNG fi sheries 2008).
Fiji became involved in the LRFT in the late 1990s but stipulated no fi shing
during spawning or aggregation periods (Ledua Ovasisi, Fiji Fisheries, 2008). Aside
from the large numbers of live fi sh removed from aggregations, which can represent
a high proportion of assembled fi sh, catches of fully ripe females can lead to
signifi cant wastage because gravid fi sh tend to undergo high mortality shortly
after capture.
8.3 Fishery Implications of Fishing Spawning Aggregations
A major challenge is to determine the extent to which exploitation of spawning
aggregations contributes to declines in marine fi sh populations. Few of the 15,500
known marine fi sh species have both the necessary biology and fi shery information
for such detailed assessment. Nonetheless, this task is critically important from a
management perspective, since many of the world’s major fi sheries support or once
supported aggregation-fi shing. The massive landings that once characterized many
highly productive fi sheries involved seasonal gatherings of fi sh at magnitudes far
greater than are seen today (Roberts 2007 ) . Presumably, aggregation-spawning
evolved, for whatever proximate reason, because, ultimately, it resulted in greater
reproductive success compared to a non-aggregating habit. Unfortunately, the very
biological characteristic, aggregation-spawning, that evidently contributes to making such species so productive may also prove to be their ‘Achilles Heel’ when