389
infer seasonal diet patterns, or to certain phases of the life cycle stages, where the
process is slower (Sinnatamby et al. 2007).
Sanderson (2009) observed that δ
15
N and δ
13
C signatures found in caudal fins
were strongly correlated to the signatures found in muscular tissue in space and
time, representing a viable alternative of non-lethal analysis. Therefore, it is not
necessary to sacrifice a fish subgroup population; instead of that few individuals
will need to be sacrificed to calibrate the conversion factor (Kelly et al. 2006).
Thus, the use of fish fins is having a more prominent place as a non-lethal alternative for stable isotope analysis, replacing traditional methods of white muscular
tissue sample, undoubtedly reducing the impact of sampling on tropical aquatic
systems. By minimizing lethal techniques, researchers may avoid undesirable
effects on the system, particularly in those cases where the same sites are being
sampled repeatedly, and the possible population-level consequences may result in
the removal of individuals for research purposes (Jardine et al. 2011). In addition,
this technique allows sampling the same individual over time, which can be very
useful in tracking patterns of individual migration or ontogenetic changes in food
ecology. More importantly, this powerful tool allows researchers to study fish that
are threatened or endangered without scarifying every individual sampled (Graham
et al. 2013).
A pioneer study using the determination of δ
15
N isotopic values in Goliath
Grouper fin rays from two different locations of similar latitudes (East and West
coast of Florida, USA), demonstrated that this non-lethal technique is quite promising for the study of near-extinction species (Tzadik et al. 2015).
In Brazil, as in other countries, the Atlantic Goliath Grouper, Epinephelus itajara
(Lichtenstein 1822) are under threat, with decreasing populations as a result of fishing pressure and habitat degradation. However, life history data for E. itajara in
Brazil are scarce and, when available, this information is fragmented and apparently
insufficient to satisfactorily assess the population status of this species along the
Brazilian coast. Due to its endangered status, non-lethal methods are very important
for biological sampling in order to cover such knowledge gaps for E. itajara and
other endangered species in Brazil. To understand the characteristics of a 1-year life
history, researchers analyzed a conserved organic matrix that holds the isotopic
ratio values over the lifetime of the individual.
Recently, studies conducted at the Florida State University have shown that
fishes dorsal fin rays can record the chronology of isotopes through non-lethal sampling. This methodology represents a great advance to study the life history characteristics of endangered species like the Atlantic Goliath Grouper and may be
replicated to other grouper species (that are of interest for management).
One of the researches conducted at the Forida State University compared ray fin
samples of E. itajara collected from three mangrove systems in the north of Espírito
Santo state in Brazil (Itaúnas – 18°25′16″S; 39°42′33″W; Conceição da Barra -
18°35′33″S; 39°44′05″W; and Barra Nova – 18°56′58″S; 39°44′41″W) to samples
collected in Ten Thousand Islands (USA). In this study, the rays number 5–7 of each
14 The Atlantic Goliath Grouper: Conservation Strategies for a Critically Endangered…
infer seasonal diet patterns, or to certain phases of the life cycle stages, where the
process is slower (Sinnatamby et al. 2007).
Sanderson (2009) observed that δ
15
N and δ
13
C signatures found in caudal fins
were strongly correlated to the signatures found in muscular tissue in space and
time, representing a viable alternative of non-lethal analysis. Therefore, it is not
necessary to sacrifice a fish subgroup population; instead of that few individuals
will need to be sacrificed to calibrate the conversion factor (Kelly et al. 2006).
Thus, the use of fish fins is having a more prominent place as a non-lethal alternative for stable isotope analysis, replacing traditional methods of white muscular
tissue sample, undoubtedly reducing the impact of sampling on tropical aquatic
systems. By minimizing lethal techniques, researchers may avoid undesirable
effects on the system, particularly in those cases where the same sites are being
sampled repeatedly, and the possible population-level consequences may result in
the removal of individuals for research purposes (Jardine et al. 2011). In addition,
this technique allows sampling the same individual over time, which can be very
useful in tracking patterns of individual migration or ontogenetic changes in food
ecology. More importantly, this powerful tool allows researchers to study fish that
are threatened or endangered without scarifying every individual sampled (Graham
et al. 2013).
A pioneer study using the determination of δ
15
N isotopic values in Goliath
Grouper fin rays from two different locations of similar latitudes (East and West
coast of Florida, USA), demonstrated that this non-lethal technique is quite promising for the study of near-extinction species (Tzadik et al. 2015).
In Brazil, as in other countries, the Atlantic Goliath Grouper, Epinephelus itajara
(Lichtenstein 1822) are under threat, with decreasing populations as a result of fishing pressure and habitat degradation. However, life history data for E. itajara in
Brazil are scarce and, when available, this information is fragmented and apparently
insufficient to satisfactorily assess the population status of this species along the
Brazilian coast. Due to its endangered status, non-lethal methods are very important
for biological sampling in order to cover such knowledge gaps for E. itajara and
other endangered species in Brazil. To understand the characteristics of a 1-year life
history, researchers analyzed a conserved organic matrix that holds the isotopic
ratio values over the lifetime of the individual.
Recently, studies conducted at the Florida State University have shown that
fishes dorsal fin rays can record the chronology of isotopes through non-lethal sampling. This methodology represents a great advance to study the life history characteristics of endangered species like the Atlantic Goliath Grouper and may be
replicated to other grouper species (that are of interest for management).
One of the researches conducted at the Forida State University compared ray fin
samples of E. itajara collected from three mangrove systems in the north of Espírito
Santo state in Brazil (Itaúnas – 18°25′16″S; 39°42′33″W; Conceição da Barra -
18°35′33″S; 39°44′05″W; and Barra Nova – 18°56′58″S; 39°44′41″W) to samples
collected in Ten Thousand Islands (USA). In this study, the rays number 5–7 of each
14 The Atlantic Goliath Grouper: Conservation Strategies for a Critically Endangered…