23
2 Ecosystem Aspects of Species That Aggregate to Spawn
such as graysby ( Cephalopholis cruentata ) and coney ( C. fulvus ), which aggressively
feed on newly settled fi shes (Kaufman and Ebersole 1984 ; Nemeth 1998 ) . Moreover,
Nassau grouper as well as tiger grouper ( Mycteroperca tigris ) were found to prey on
Indo-Pacifi c lionfi sh ( Pterois volitans ) (Maljković et al. 2008 ) , which has recently
invaded the Atlantic coast of North America and many locations throughout the
Caribbean (Whitfi eld et al. 2002 , Hamner et al. 2007a , Snyder and Burgess 2007 ) .
Unfortunately, Nassau grouper , tiger grouper and other aggregating groupers
have been fi shed heavily throughout the region (Olsen and LaPlace 1978 ; Sadovy
et al. 1994a ; Sadovy 1997 ; Aguilar-Perera 2006 ) , an unforeseen consequence of
lack of fi shery management that reduces trophic integrity and biological diversity and may be a factor allowing for the spread of Indo-Pacifi c lionfi sh and other
invasive species.
This chapter examines aggregating species within a broad ecosystem context
with a particular focus on the spatial scales of migration to, and movements around,
fi sh spawning aggregation (FSA) sites, the methods used to study these movement
patterns (Sect. 2.1 ), migration pathways and habitat linkages between home sites
and spawning areas (Sect. 2.2 ) and the potential impacts of aggregating species on
local food webs via predator-prey interactions (Sect. 2.3 ). This chapter also examines how these spatial aspects of migrating species can be integrated into an ecosystem approach to fi sheries management (Sect. 2.4 ).
To better understand these various spatial and ecological aspects of FSA’s, a brief
description of reproduction in aggregating species is warranted. A wide diversity of
species form spawning aggregations (Chap. 1, Table 1 ) and all migrate from home
ranges or feeding sites to specifi c locations for reproduction. Two general categories of
aggregation can be defi ned although some species share features of both (Chap. 1 ).
Resident aggregating species such as surgeonfi shes and parrotfi shes can often be
found in various sized groups foraging across a reef throughout the day (Ogden and
Buckman 1973 ; Robertson 1983 ) . These smaller species may have home ranges
located only a few tens or hundreds of metres to a maximum of a few km from
spawning sites. Therefore their migration distances are short. Transient aggregating
species such as groupers and snappers usually consist of widely dispersed solitary
individuals that remain within home ranges during the non-reproductive period.
For these larger species spawning sites may be tens to hundreds of kilometres away,
although a proportion of the spawning adults may live in close proximity to the
aggregation site (Hutchinson and Rhodes 2010 ) . At the onset of the reproductive
season, various large-scale environmental cues such as water temperature or daylength, or correlates of these, may initiate migration of the spawning population
(Nemeth 2009 ) . Spawning seasons typically last 2–3 months for transient aggregating species while resident aggregating species can spawn on a monthly or even
daily basis throughout much of the year (Chap. 5 ) (Sadovy de Mitcheson et al.
2008 ) . The mode of spawning ranges from gamete release a few metres from
the substrate between an individual male and female pair or between a male
spawning with individual females within a harem, to massive group-spawning
in mid-water between a female and several males (Domeier and Colin 1997 ) .
2 Ecosystem Aspects of Species That Aggregate to Spawn
such as graysby ( Cephalopholis cruentata ) and coney ( C. fulvus ), which aggressively
feed on newly settled fi shes (Kaufman and Ebersole 1984 ; Nemeth 1998 ) . Moreover,
Nassau grouper as well as tiger grouper ( Mycteroperca tigris ) were found to prey on
Indo-Pacifi c lionfi sh ( Pterois volitans ) (Maljković et al. 2008 ) , which has recently
invaded the Atlantic coast of North America and many locations throughout the
Caribbean (Whitfi eld et al. 2002 , Hamner et al. 2007a , Snyder and Burgess 2007 ) .
Unfortunately, Nassau grouper , tiger grouper and other aggregating groupers
have been fi shed heavily throughout the region (Olsen and LaPlace 1978 ; Sadovy
et al. 1994a ; Sadovy 1997 ; Aguilar-Perera 2006 ) , an unforeseen consequence of
lack of fi shery management that reduces trophic integrity and biological diversity and may be a factor allowing for the spread of Indo-Pacifi c lionfi sh and other
invasive species.
This chapter examines aggregating species within a broad ecosystem context
with a particular focus on the spatial scales of migration to, and movements around,
fi sh spawning aggregation (FSA) sites, the methods used to study these movement
patterns (Sect. 2.1 ), migration pathways and habitat linkages between home sites
and spawning areas (Sect. 2.2 ) and the potential impacts of aggregating species on
local food webs via predator-prey interactions (Sect. 2.3 ). This chapter also examines how these spatial aspects of migrating species can be integrated into an ecosystem approach to fi sheries management (Sect. 2.4 ).
To better understand these various spatial and ecological aspects of FSA’s, a brief
description of reproduction in aggregating species is warranted. A wide diversity of
species form spawning aggregations (Chap. 1, Table 1 ) and all migrate from home
ranges or feeding sites to specifi c locations for reproduction. Two general categories of
aggregation can be defi ned although some species share features of both (Chap. 1 ).
Resident aggregating species such as surgeonfi shes and parrotfi shes can often be
found in various sized groups foraging across a reef throughout the day (Ogden and
Buckman 1973 ; Robertson 1983 ) . These smaller species may have home ranges
located only a few tens or hundreds of metres to a maximum of a few km from
spawning sites. Therefore their migration distances are short. Transient aggregating
species such as groupers and snappers usually consist of widely dispersed solitary
individuals that remain within home ranges during the non-reproductive period.
For these larger species spawning sites may be tens to hundreds of kilometres away,
although a proportion of the spawning adults may live in close proximity to the
aggregation site (Hutchinson and Rhodes 2010 ) . At the onset of the reproductive
season, various large-scale environmental cues such as water temperature or daylength, or correlates of these, may initiate migration of the spawning population
(Nemeth 2009 ) . Spawning seasons typically last 2–3 months for transient aggregating species while resident aggregating species can spawn on a monthly or even
daily basis throughout much of the year (Chap. 5 ) (Sadovy de Mitcheson et al.
2008 ) . The mode of spawning ranges from gamete release a few metres from
the substrate between an individual male and female pair or between a male
spawning with individual females within a harem, to massive group-spawning
in mid-water between a female and several males (Domeier and Colin 1997 ) .