of sessile (attached) organisms such as bivalve mollusks
(Relini et al., 1994). Japanese researchers have investigated the deployment of artificial reefs as structures to
help divert ocean currents to facilitate upwelling that
brings nutrients nearer to the surface to enhance phytoplankton productivity and, in turn, increase coastal fish
abundance and growth (Okano et al., 2011).
The complete use of artificial reefs has yet to be fully
explored. Interestingly, at least one company (www.
eternalreefs.com) makes use of artificial reefs as human
burial sites.
Concepts
The general idea behind deploying artificial reefs to
enhance fisheries is related to either one or both of the
two assumptions long argued by fisheries scientists. These
assumptions are that artificial reefs attract fishery
resources to a site, or they increase the productivity of
fisheries resources. Clearly both concepts are viable and
each can have utility in fisheries management. To date,
however, both these assumptions are recognized, but little
scientific testing has been done to allow proper rejection
of either hypothesis in the attraction versus production
debate (Bortone, 2006; Bortone, 2011).
Bohnsack (1989) diagrammatically summarized the
general perspective of the attraction and production perspectives based on observations and published research.
His perspective was that attraction and production were
either ends of a continuum with regard to several attributes.
In summary, artificial reefs that functioned more for production than attraction had low reef availability and low
fishing intensity. They were inhabited by species that were
habitat limited (as opposed to recruitment limited), more
reef dependent, and, behaviorally, more territorial, demersal, and with high site affinity (philopatry). Polovina
(1991) further clarified the attraction/production argument
relative to fisheries. He indicated that if artificial reefs
merely served to concentrate fish in an area, then the same
biomass could be caught with less effort. If the artificial reef
attracted fish from other areas, then fishing yield could
increase as long as fishing effort increased. Lastly, if artificial reefs increased the carrying capacity of an area, then
both total biomass and exploitable biomass should occur.
The presumption by both Bohnsack (1989) and Polovina
(1991) is that attraction is the opposite of production.
Bortone (2008) proposed that attraction and production
were both at play in the response species made to the presence of artificial reef structure. He reasoned that some species could be both attracted to structure and that, for some
species, the carry capacity of an area could also allow an
increase in biomass as well (e.g., octopus and spiny lobster). Oppositely, some species are neither attracted nor do
their populations increase because of the presence of artificial reefs (e.g., species that show no affinity for reefs). Most
certainly, a variety of species show varying degrees of
attraction to artificial reefs with varying degrees of biomass
facilitation because of the reef’s presence.
The conundrum might be resolved if resource managers
could determine the features of target species that are
enhanced by deploying artificial reefs. This means that
some species and their associated fisheries may, indeed,
benefit from the deployment of an artificial reef, in terms
of both attraction and production, while others may not.
This implies that, at least if fisheries enhancement is the
goal of an artificial reef deployment, each reef should have
an objective directed toward a particular species and its
life history feature that can be enhanced because of
the reef.
Special features of estuarine artificial reefs
While there has been some attention given to the deployment of artificial reefs in estuaries (e.g., Bortone et al.,
1994; Chapman and Clynick, 2006), they have received
only passing attention to date, although artificial reefs
have been used as mitigation in estuaries (Foster et al.,
1994). It should be noted that the principles applied to artificial reefs in other aquatic systems are probably no different when applied to estuaries. Generally, diversity issues
are less important in estuaries, and changes in salinity,
tidal flow, and turbidity add extra dimensions when considering the results of artificial reef deployments. Their
more recent usage in estuaries has been via the deployment of oyster reefs (Coen and Luckenbach, 2000). This
is a popular estuarine enhancement activity conducted by
many resource managers. The extrapolation of deploying
oyster reefs as consideration of an estuarine artificial reef
should not be overlooked by artificial reef researchers.
Current investigations
Research on artificial reefs continues, but, as Bortone
(2011) warned, unless clear objectives are included in
these investigative efforts, the resolution of the attraction
versus production argument will remain elusive. Particularly disconcerting is the feature that current research
results are unable to answer many of the questions
resource managers face. While artificial reefs have long
been touted as offering a solution to many fisheries management issues, their lack of specific prescription in
management will continue to exclude artificial reefs from
the proverbial “managers toolbox” until these and many
other issues associated with artificial reefs are programmatically resolved.
Gaps in current knowledge
Bohnsack and Sutherland (1985) and Bortone (2006,
2001) presented arguments for new directions in artificial
reef research. Each of these reviews indicated the overriding gap in artificial reef research is the lack of application
of artificial reefs as a reliable and predictable option for
natural resource managers. Resolution of the attraction/
production hypotheses plays a prominent role in resolving
this issue. More importantly, however, is the need to determine the life history “bottlenecks” that are likely to be
relieved by the deployment of a reef. One example of
40
ARTIFICIAL REEF
(Relini et al., 1994). Japanese researchers have investigated the deployment of artificial reefs as structures to
help divert ocean currents to facilitate upwelling that
brings nutrients nearer to the surface to enhance phytoplankton productivity and, in turn, increase coastal fish
abundance and growth (Okano et al., 2011).
The complete use of artificial reefs has yet to be fully
explored. Interestingly, at least one company (www.
eternalreefs.com) makes use of artificial reefs as human
burial sites.
Concepts
The general idea behind deploying artificial reefs to
enhance fisheries is related to either one or both of the
two assumptions long argued by fisheries scientists. These
assumptions are that artificial reefs attract fishery
resources to a site, or they increase the productivity of
fisheries resources. Clearly both concepts are viable and
each can have utility in fisheries management. To date,
however, both these assumptions are recognized, but little
scientific testing has been done to allow proper rejection
of either hypothesis in the attraction versus production
debate (Bortone, 2006; Bortone, 2011).
Bohnsack (1989) diagrammatically summarized the
general perspective of the attraction and production perspectives based on observations and published research.
His perspective was that attraction and production were
either ends of a continuum with regard to several attributes.
In summary, artificial reefs that functioned more for production than attraction had low reef availability and low
fishing intensity. They were inhabited by species that were
habitat limited (as opposed to recruitment limited), more
reef dependent, and, behaviorally, more territorial, demersal, and with high site affinity (philopatry). Polovina
(1991) further clarified the attraction/production argument
relative to fisheries. He indicated that if artificial reefs
merely served to concentrate fish in an area, then the same
biomass could be caught with less effort. If the artificial reef
attracted fish from other areas, then fishing yield could
increase as long as fishing effort increased. Lastly, if artificial reefs increased the carrying capacity of an area, then
both total biomass and exploitable biomass should occur.
The presumption by both Bohnsack (1989) and Polovina
(1991) is that attraction is the opposite of production.
Bortone (2008) proposed that attraction and production
were both at play in the response species made to the presence of artificial reef structure. He reasoned that some species could be both attracted to structure and that, for some
species, the carry capacity of an area could also allow an
increase in biomass as well (e.g., octopus and spiny lobster). Oppositely, some species are neither attracted nor do
their populations increase because of the presence of artificial reefs (e.g., species that show no affinity for reefs). Most
certainly, a variety of species show varying degrees of
attraction to artificial reefs with varying degrees of biomass
facilitation because of the reef’s presence.
The conundrum might be resolved if resource managers
could determine the features of target species that are
enhanced by deploying artificial reefs. This means that
some species and their associated fisheries may, indeed,
benefit from the deployment of an artificial reef, in terms
of both attraction and production, while others may not.
This implies that, at least if fisheries enhancement is the
goal of an artificial reef deployment, each reef should have
an objective directed toward a particular species and its
life history feature that can be enhanced because of
the reef.
Special features of estuarine artificial reefs
While there has been some attention given to the deployment of artificial reefs in estuaries (e.g., Bortone et al.,
1994; Chapman and Clynick, 2006), they have received
only passing attention to date, although artificial reefs
have been used as mitigation in estuaries (Foster et al.,
1994). It should be noted that the principles applied to artificial reefs in other aquatic systems are probably no different when applied to estuaries. Generally, diversity issues
are less important in estuaries, and changes in salinity,
tidal flow, and turbidity add extra dimensions when considering the results of artificial reef deployments. Their
more recent usage in estuaries has been via the deployment of oyster reefs (Coen and Luckenbach, 2000). This
is a popular estuarine enhancement activity conducted by
many resource managers. The extrapolation of deploying
oyster reefs as consideration of an estuarine artificial reef
should not be overlooked by artificial reef researchers.
Current investigations
Research on artificial reefs continues, but, as Bortone
(2011) warned, unless clear objectives are included in
these investigative efforts, the resolution of the attraction
versus production argument will remain elusive. Particularly disconcerting is the feature that current research
results are unable to answer many of the questions
resource managers face. While artificial reefs have long
been touted as offering a solution to many fisheries management issues, their lack of specific prescription in
management will continue to exclude artificial reefs from
the proverbial “managers toolbox” until these and many
other issues associated with artificial reefs are programmatically resolved.
Gaps in current knowledge
Bohnsack and Sutherland (1985) and Bortone (2006,
2001) presented arguments for new directions in artificial
reef research. Each of these reviews indicated the overriding gap in artificial reef research is the lack of application
of artificial reefs as a reliable and predictable option for
natural resource managers. Resolution of the attraction/
production hypotheses plays a prominent role in resolving
this issue. More importantly, however, is the need to determine the life history “bottlenecks” that are likely to be
relieved by the deployment of a reef. One example of
40
ARTIFICIAL REEF