Research Article |
Corresponding author: Marcus Rodrigues da Costa ( marcusrc@id.uff.br ) Academic editor: Susan Barbieri
© 2018 Marcus Rodrigues da Costa, Rafael de Almeida Tubino, Cassiano Monteiro-Neto.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Costa M, Tubino R, Neto C (2018) Length-based estimates of growth parameters and mortality rates of fish populations from a coastal zone in the Southeastern Brazil. Zoologia 35: 1-8. https://doi.org/10.3897/zoologia.35.e22235
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Small-scale fisheries in Brazil contribute to a significant share of total fish production, accessing a large variety of species. Life history parameters from these resources are important for their management and conservation, based on primary data. The objective of this article is to generate growth parameters and mortality rates of ten fish populations from a coastal zone in Southeastern Brazil. Monthly samples were taken between January 2011 and November 2014 from landings of the beach-seine fishery in an area adjacent to the entrance of the Guanabara Bay. All fishes were measured (total length) and weighed. The length-weight relationships (LWR) were estimated by linear regression analysis on log-transformed data of the equation: W = aLb. The Von Bertalanffy Growth Function (VBGF) was fitted to size-at-age data to obtain growth parameters (K, L∞). The length-converted catch curve was used for estimating the instantaneous total mortality (Z). Taylor’s equations provided an independent estimate of the natural mortality (M) and longevity. The difference between Z and M derived Fishing mortality (F). A total of 2,938 individuals from ten fish species were used to determine the length-weight relationships. Harengula clupeola (Cuvier, 1829) has a new maximum length record for the FishBase LWR database. Sardinella brasiliensis (Steindachner, 1879) presented the smallest and largest size recorded for LWR observed in the literature and FishBase database. Upeneus parvus showed the greatest total length, while Trichiurus lepturus Linnaeus, 1758, Orthopristis ruber (Cuvier, 1830) and Dactylopterus volitans (Linnaeus, 1758) presented the smallest sizes for LWR in FishBase. The other species showed parameters within the expected values for each group. The performance index combining information from K and L∞ presented values between 2.32 and 3.76 and were considered appropriate for the populations evaluated. Fishing was the primary source of mortality for Caranx crysos (Mitchill, 1815), Eucinostomus argenteus Baird & Girard, 1855, S. brasiliensis and U. parvus, and less important for Cynoscion jamaicensis (Vaillant & Bocourt, 1883), D. volitans, O. ruber, Selene setapinnis (Mitchill, 1815), T. lepturus and H. clupeola. The parameters generated may be used for the management and conservation of the species’ stocks.
Ichthyofauna, length-weight relationships, life history, shallow waters, small-scale fisheries
Direct readings of hard structures (e.g., otoliths, spines, vertebrae) to estimate the age of fish, or indirect estimates based on length distribution data over time are traditional methods to determine growth parameters of fish populations (
The lack of growth and mortality estimates is widespread for coastal marine fish populations. These are essential parameters for modeling population dynamics of fish stocks and ecosystems (
In Brazil, small-scale fisheries contribute a significant share of total fish production, accessing a large variety of species. These fisheries often exploit coastal fishery resources, as the fleet is mostly limited by size and technology (
The Itaipu coastal zone (22°53’14” S, 43°04’00” W) covers an intensive small-scale (artisanal) fishery established in the area since the 18th century. Today, nearly 110 fishermen realize their catches in areas down to 50 m deep (
We monitored the artisanal beach-seine fishery landings in Itaipu on a monthly basis from January 2001 to November 2004, recording catch composition, abundance and fish size structures. Beach-seine operations were considered as boat trips, and teams of two to three observers at the landing site monitored all trips during the sampling day. Once a month one beach-seine operation was fully monitored to record the whole fishing process, including the sorting and marketing of the catch. All collected specimens (license SISBIO #15787-1) were placed in plastic bags, labeled and stored on ice during transport to the laboratory where they were screened and identified at the lowest taxonomic level (e.g.
W = aLb
where W is the total weight of fishes (g), a is the coefficient related to body shape, L is the total length (cm), and b is an exponent related to changes in body shape (
log(W) = log (a) + b log (L)
estimated parameters ‘a’ and ‘b’; extreme outlier values were excluded from the analyses. Additionally, 95% confidence limits (CL) of ‘a’ and ‘b’ were estimated. The r-squared (R2) Pearson coefficient provided an estimate of model fit.
Growth rates were calculated using the seasonal von Bertalanffy’s equation, where Lt is the length of the fish (cm) at age t (year), L∞ is the asymptotic total length (cm), k is the constant growth rate (year–1), and t0 (year) is the nominal age at which fish length is considered to be zero. The k constant was calculated in the FISAT II software (
The best growth curve was fitted, based on the “Rn value” a non-parametric goodness of fit index (
log(–t0) = log – 0.3922 – 0.2752 L∞ – 1.038 logk
The values of L∞ and L50 (estimated from L∞) were found using the length of the largest individual (Lmax) and
log(L∞) = 0.044 + 0.9841 × log(Lmax)
and
log(L50) = 0.8979 × log(L∞) – 0.0782
To standardize the data, t0 was considered to be zero for all populations. The length-converted catch curve method (
M = 2.996/A 0.95%
Fishing mortality (F) was derived from the difference between Z and M, and the exploitation ratio (E) from fishing mortality/total mortality. Longevity (A 0.95%), defined as the time the individual takes to reach 95% of the asymptotic length, was estimated based on the formula proposed by
tmax = t0 + 2.996/k
Growth performance indexes (
θ = log(k) + 2 × log(L∞)
The indices obtained were compared with values from other stocks of the same species available on FishBase (http://www.fishbase.org) or the literature.
A total of 2,938 specimens representing ten different fish species (eight families) were used to determine the length-weight relationships (LWR). A new maximum length was recorded for Harengula clupeola (Cuvier, 1829) (22.5 cm TL). The data set does not provide first records for the other species in the FishBase database, but present larger and smaller size amplitudes than those previously reported for Brazil and the FishBase. Upeneus parvus Poey, 1852 presented a highest total length; Sardinella brasiliensis (Steindachner, 1879) presented the lowest and highest TL while Trichiurus lepturus Linnaeus, 1758, Orthopristis ruber (Cuvier, 1830) and Dactylopterus volitans (Linnaeus, 1758) presented the lowest TL values. Table
Sample size (n), ranges of total length (LT) and weight (TW) of fish species. Values and confidence limits (CL) of a and b, coefficients of determination (R2) and type of growth (ALO+, positive allometric; ALO-, negative allometric and ISO, isometric).
Family | Scientific name | n | TL (min – max) | TW (min – max) | a | -a CL | a CL | b | -b CL | b CL | R2 | t calc (α 0.05) | Type growth |
Clupeidae | Harengula clupeola | 430 | 3.2–22.5 | 1.0–109.0 | 0.007 | 0.006 | 0.007 | 3.22 | 3.16 | 3.28 | 0.96 | 7.10 | ALO+ |
Sardinella brasiliensis | 310 | 3.2–25.5 | 0.2–119.0 | 0.005 | 0.004 | 0.006 | 3.13 | 3.06 | 3.19 | 0.97 | 3.85 | ALO+ | |
Dactylopteridae | Dactylopterus volitans | 246 | 1.5–31.9 | 2.0–358.0 | 0.021 | 0.017 | 0.025 | 2.76 | 2.69 | 2.84 | 0.95 | -6.19 | ALO- |
Carangidade | Caranx crysos | 162 | 10.2–33.5 | 16.0–473.0 | 0.008 | 0.005 | 0.011 | 3.14 | 3.03 | 3.25 | 0.95 | 2.48 | ALO+ |
Selene setapinnis | 318 | 3.5–35.0 | 1.0–463.0 | 0.015 | 0.014 | 0.016 | 2.94 | 2.91 | 2.97 | 0.99 | -4.16 | ALO- | |
Gerreidae | Eucinostomus argenteus | 475 | 4.6–21.0 | 1.0–110.0 | 0.009 | 0.008 | 0.011 | 3.14 | 3.08 | 3.20 | 0.96 | 4.50 | ALO+ |
Haemulidae | Orthopristis ruber | 287 | 3.5–27.0 | 0.9–250.0 | 0.015 | 0.012 | 0.016 | 3.01 | 2.95 | 3.08 | 0.97 | 0.44 | ALO+ |
Scianidae | Cynoscion jamaicensis | 135 | 5.4–27.8 | 5.0–300.0 | 0.010 | 0.007 | 0.014 | 3.06 | 2.96 | 3.17 | 0.96 | 1.19 | ISO |
Mullidae | Upeneus parvus | 230 | 5.5–23.0 | 1.0–180.0 | 0.004 | 0.003 | 0.005 | 3.41 | 3.31 | 3.51 | 0.95 | 7.96 | ALO+ |
Trichiuridae | Trichiurus lepturus | 345 | 4.2–138.0 | 3.0–2,000.0 | 0.001 | 0.001 | 0.001 | 3.02 | 2.95 | 3.09 | 0.96 | 0.50 | ISO |
Population estimates obtained from seasonally adjusted length frequency data were achieved for most important fish species captured by the beach seine fishery. Table
In general, our θ values are within the range of θ values from the literature to all species evaluated, except for U. parvus from which growth parameters were inexistent for the coast of Brazil. Fishing was the most important source of mortality for Caranx crysos (Mitchill, 1815), Eucinostomus argenteus Baird & Girard, 1855, S. brasiliensis and U. parvus, and less important for Cynoscion jamaicensis (Vaillant & Bocourt, 1883), D. volitans, O. ruber, Selene setapinnis (Mitchill, 1815), T. lepturus and H. clupeola.
Longevity estimates related to the growth constant (k) are within the expected values for all species evaluated, corresponding to the age at which 95% of the population would die from natural causes.
Values of constant growth rate (k; year-1), asymptotic total length (L∞; cm), nominal age at which fish length is considered zero (t0; year), C (seasonal oscillation amplitude; Cº), Wp (winter point); growth performance index (θ; Phi); instantaneous total mortality (Z), natural mortality (M), fishing mortality (F), exploitation ratio (E), length of first sexual maturity (L50), proportion of individuals below the length of first sexual maturity (n < L50;%) and longevity (A0.95%; years) by small scale fisheries in Itaipu costal zone.
Family | Scientific name | K (year-1) | L∞ | t0 | C | Wp | θ (Phi) | Rn value | Z | M | F | E | L50 | n < L50 (%) | A 0.95% |
Clupeidae | Harengula clupeola | 0.43 | 23.68 | -0.41 | 0.25 | 0.91 | 2.38 | 0.678 | 1.11 | 0.97 | 0.14 | 0.13 | 14.3 | 84.0 | 6.56 |
Sardinella brasiliensis | 0.26 | 23.68 | -0.80 | 0.25 | 0.67 | 2.16 | 0.519 | 1.64 | 0.70 | 0.94 | 0.57 | 15.8 | 85.5 | 10.73 | |
Dactylopteridae | Dactylopterus volitans | 0.30 | 33.58 | -0.57 | 0.25 | 0.91 | 2.53 | 0.403 | 0.95 | 0.70 | 0.25 | 0.26 | 19.5 | 72.4 | 9.42 |
Carangidade | Caranx crysos | 0.65 | 35.26 | -0.21 | 0.25 | 0.65 | 2.91 | 0.965 | 2.94 | 1.14 | 1.80 | 0.61 | 20.4 | 7.4 | 4.40 |
Selene setapinnis | 0.49 | 36.84 | -0.30 | 0.25 | 0.10 | 2.82 | 0.417 | 1.22 | 0.94 | 0.28 | 0.23 | 21.2 | 76.7 | 5.81 | |
Gerreidae | Eucinostomus argenteus | 0.47 | 22.11 | -0.38 | 0.25 | 0.66 | 2.36 | 0.393 | 2.68 | 1.06 | 1.62 | 0.60 | 13.5 | 33.9 | 6.00 |
Haemulidae | Orthopristis ruber | 0.38 | 28.42 | -0.44 | 0.25 | 0.91 | 2.49 | 0.753 | 1.09 | 0.86 | 0.23 | 0.21 | 16.9 | 86.1 | 7.44 |
Scianidae | Cynoscion jamaicensis | 0.36 | 29.20 | -0.48 | 0.25 | 0.83 | 2.49 | 0.586 | 1.02 | 0.82 | 0.20 | 0.20 | 17.3 | 2.2 | 7.84 |
Mullidae | Upeneus parvus | 0.36 | 24.21 | -0.51 | 0.25 | 0.41 | 2.32 | 0.937 | 1.83 | 0.87 | 0.97 | 0.53 | 14.6 | 87.0 | 7.81 |
Trichiuridae | Trichiurus lepturus | 0.64 | 145.26 | -0.10 | 0.25 | 0.49 | 4.13 | 0.803 | 0.96 | 0.77 | 0.19 | 0.20 | 71.1 | 65.5 | 4.58 |
This study was conducted to determine some of the key management parameters of growth, mortalities, exploitation rate, longevity and size of the first maturity for fish species caught by the beach-seine artisanal fishery conducted within the Itaipu RESEX, a TURF type protected area. Estimates of population parameters are essential for understanding the biological characteristics of fish species, in particular, those targeted by commercial fisheries (
The relative growth parameters reported are within the range documented in the literature for all ten species. These are widely distributed with a widespread occurrence on the South-southeastern coast of Brazil (
Beach seining is one of the oldest and most traditional fishing methods employed in Brazil, practiced on dissipative sandy beaches with a gentle slope and vast areas to extend the net (
The population parameters recorded in the present study suggests the existence of a fish fauna adapted to various local environmental constraints (spatial, temporal, or both), reflecting the habitat partitioning as they undergo biological development. Some of these species (e.g. C. crysos, E. argenteus, H. clupeola, and S. brasiliensis) are true “r” strategists, showing opportunistic life history strategies exploring empty ecological niches, spawning large batches of eggs without parental care and subjected to very high mortality rates during the first weeks of life. Individuals usually have a short lifespan and habitat carrying capacity is not a restrictive factor. This assemblage forms the bottom of the food chain.
On the other hand, species such C. jamaicensis, D. volitans, O. ruber, S. setapinnis, and T. lepturus, showed the “K” strategist life history strategy. Individuals are reaching larger sizes at a slow growth with low mortality rates. There is a greater parental care investment in the brood with offsprings showing higher survival probability in well busy niches. Such species are suited for life in resilient environments (
Natural mortality rate M and longevity showed dimensional reciprocity, but their precise relationship is complex and depends on both natural factors (e.g. changes in M with age due to senescence) and technical aspects such as sampling (e.g. the type of fishing net) and age-determination (
Using M and Z estimates, the current fishing mortality (F) was calculated for each species. Comparing the estimated values for M and F, it is possible to conclude that the fishery was the most important source of mortality (F > M) for C. crysos, E. argenteus, H. clupeola and U. parvus stocks. Fishing and natural mortality are practically the same for C. jamaicensis, whereas for other species fishing is less important than the other sources of mortality (F < M). Thus, from these results, it is plausible to assume that the stocks showing the “r” strategist behavior were under greater fishing pressure than the other species in question. Also, the levels of exploration (E) in the studied populations corroborate our hypothesis related to F. In fact,
Length-frequency data were collected routinely for fisheries management, as part of exploratory surveys (
Within the Itaipu coastal zone, this beach seine fishery provided subsistence and established the modes of social reproduction of the Itaipu fishers for more than two centuries (
The authors would like to thank Coordenação de Aperfeiçoamento de Pessoal do Ensino Superior (Capes) for the financial support provided through the post-doctoral fellowship PNPD to R.A. Tubino. Cassiano Monteiro-Neto holds a Research Productivity fellowship from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). We also thank the fishers from Itaipu RESEX who contributed for this research. L. Loto elaborated the area map. We greatly appreciated the field and laboratory assistance of all trainees of the ECOPESCA Laboratory. This work was financially supported by Fundação Carlos Chagas de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ E 26/112.613/2012) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq 406249/2012-1).