Length–weight and length–length relationships of fishes from the Ouémé River in Bénin (West Africa)

The relationships between total (TL) and standard (SL) lengths for 50 fish species and between TL and wet weight for 52 fish species caught in the Ouémé River are presented. Relationships between TL and SL are linear. Between TL and weight, the relationships are of the form TW = aTL^b. The b values range from 2.3307 to 3.5185. Student's t‐test revealed that 38.5% of the species have b values significantly different from 3.     

Condition factor,length–weight and length–length relationships of an endangered fish Ompok pabda (Hamilton 1822) (Siluriformes: Siluridae) from the River Gomti,a tributary of the River Ganga,India

The present study describes the condition factor, length‐weight and length‐length relationships for an endangered freshwater fish species Ompok pabda (Hamilton) of the family Siluridae from the River Gomti in Northern India. The values of regression parameter b ranged from 2.81 to 3.32 (r² > 0.90). During the pre‐monsoon, the allometric coefficient b of the LWR was close to isometric value (b = 3.08) allometric (b = 2.87), although it suggested negative allometric growth in monsoon periods while positive growth in post‐monsoon. The condition factor values ranged from 0.672 to 0.744. Results of the present study could be useful to help in conservation and sustainable fisheries management of this endangered species.     

Length–weight relationships of 40 freshwater fish species from two decades of monitoring in Flanders (Belgium)

Nearly 263 000 individual length–weight (L/W) data, collected during 2839 fish stock assessments between 1992 and 2009, were used to calculate L/W relationships (W = aL^b) of 40 freshwater fish species from Flanders (Belgium). Roach Rutilus rutilus, perch Perca fluviatilis, three‐spine stickleback Gasterosteus aculeatus, gudgeon Gobio gobio and European eel Anguilla anguilla were the most abundant species in our surveys. Mean a and b values were in accordance with those available in FishBase. Mean b across all examined species is 3.094 (95% CL = 3.041 to 3.148) indicating a tendency towards slightly positive allometric growth in most fishes (thirty‐three species with b > 3). On the basis of a form factor equation, we characterized 2 species as ‘eel‐like’, 7 as ‘elongated’, 22 as ‘fusiform’ and 9 species as ‘short and deep’. This paper adds a substantial dataset to the yet scarcely available a and b values of European populations of freshwater fish species.     

Gonads annual development of Kelee shad, <Emphasis Type="Italic">Hilsa kelee</Emphasis> (Cuvier, 1829) from the coastal waters of Pakistan and its spawning ecology

Annual reproductive cycle and spawning ecology of Kelee shad, Hilsa kelee were studied. The sex ratios did not exhibit as 1: 1; whereas 69.19% were females. On the basis of histological examination, the maturity of female gonads of H. kelee was categorized in eight developmental stages: immature, developing, fully developed, hydrated, running ripe, partially spent, spent and post spawning. Whereas males of this species were categorized in five developmental stages: immature, developing, ripe, partially spent and spent. This fish is repeatedly spawner and spawns twice per year: in April to June and August to October. The values of exponent b in the length weight regressions (W = al ^b ) slightly varied in males b = 3.133, R ² = 0.96 and P < 0.01 and females b = 3.143, R ² = 0.95 and P < 0.001. The linear regressions of length-weight relationships were significant for both males and females.     

Daily Rhythms of Metabolic Rate and Body Temperature of Two Murids from Extremely Different Habitats

Daily circadian rhythms of body temperature (T_b) and oxygen consumption (VO₂) were measured in two murid species, which occupy extremely different habitats in Israel. The golden spiny mouse (Acomys mssalus) is a diurnal murid distributed in arid and hot parts of the great Syrio-African Rift Valley, while the broad-toothed field mouse (Apodeinns mystacinus) is a nocturnal species that inhabits the Mediterranean woodlands. In both species, the daily rhythms of T_b and VO₂ are entrained by the photoperiod. Under laboratory experimental conditions (ambient temperature T_a = 33^oC and photoperiod regime of 12L: 12D), Acomys russatus exhibits a tendency towards a nocturnal activity pattern, compared to the diurnal activity displayed by this species under natural conditions. Under the same photoperiod regime and at T_a = 28^oC, Apodemus mystacinus displays nocturnal activity, as observed under natural conditions. The maximal values of T_b were recorded in Acomys russatus at midnight (23:50 h), while the maximal values of VO₂ were recorded at the beginning of the dark period (18:20 h). In Apodemus mystacinus, the maximal values of T_b and VO₂ were recorded at 23:40 and 20:00 h, respectively. The ecophysiological significance of these results is discussed further.     

Length–weight relationships of seven myctophid fishes (Myctophiformes: myctophidae) in the South China Sea

The study included 546 specimens of seven myctophid fish species from the South China Sea (captured during June 2015 by bottom and mid‐water trawls). Length‐weight relationships (LWRs), W = aL^b, were estimated using standard length. The species belong to four genera. The values for the parameter a ranged from 0.006 to 0.022, while the b values ranged from 2.710 to 3.476 (Range of r² values: .938 to .971). According to FishBase, this study presents the first LWRs for these species, including two maximum standard lengths for Diaphus chrysorhynchus and Notoscopelus resplendens.     

Length–weight relationships of an invasive cyprinid fish (Carassius gibelio) from 12 Greek lakes in relation to their trophic states

The length–weight relationships of the cyprinid fish Carassius gibelio (Bloch, 1782) are described for the 12 most important lakes of Greece. Carassius gibelio is an allogynogenetic fish species, which was introduced into Greek lakes during the late 1970s. The values of the exponent b of the length–weight relationships ranged from 2.33 to 3.38, and varied with the trophic state of the lake. In eutrophic lakes these b values were significantly (P < 0.001) lower than in oligotrophic or mesotrophic lakes. Relationships between the b values and phosphorus concentrations were logarithmic: b = 1.37–0.13 log (PO₄‐P); total length, fork length and standard length were linear (in all cases: r² > 0.95). In most of the lakes, populations consisted of females, with the exception of Pamvotis, Doirani and Koronia lakes where a small proportion were males.     

Length–weight relationships of the invasive topmouth gudgeon (Pseudorasbora parva) in ten lakes in the UK

The topmouth gudgeon (Pseudorasbora parva) is a species that is becoming invasive in UK waters. Few biological studies have been completed on the species in this extended range, resulting in sparse information in some aspects of their invasion biology. Regarding length–weight relationships, this is remedied in this study by providing data for 10 lake populations in the UK. Using fish length range 2.5–11.8 cm, values of a and b in the length–weight equation are provided. Values of b ranged between 2.76 and 3.32. Across all lakes, the relationship was W = 0.011L^3.03, with weight in grams and length (fork) in cm.     

Length–weight and length–length relationships of fish species from the Chi River,northeastern Thailand

The relationships of total length (TL), fork length (FL) and standard length (SL) are presented for four fish species and the relationships between TL and wet weight for 23 fish species from the Chi River in northeastern Thailand. All length–length relationships were linear (r² > 0.95). Slope (b) of the length–weight relationships showed values between 2.5073 and 3.4896.     

Cube law, condition factor and weight–length relationships: history, meta-analysis and recommendations

This study presents a historical review, a meta‐analysis, and recommendations for users about weight–length relationships, condition factors and relative weight equations. The historical review traces the developments of the respective concepts. The meta‐analysis explores 3929 weight–length relationships of the type W = aL^b for 1773 species of fishes. It shows that 82% of the variance in a plot of log a over b can be explained by allometric versus isometric growth patterns and by different body shapes of the respective species. Across species median b = 3.03 is significantly larger than 3.0, thus indicating a tendency towards slightly positive‐allometric growth (increase in relative body thickness or plumpness) in most fishes. The expected range of 2.5 < b < 3.5 is confirmed. Mean estimates of b outside this range are often based on only one or two weight–length relationships per species. However, true cases of strong allometric growth do exist and three examples are given. Within species, a plot of log a vs b can be used to detect outliers in weight–length relationships. An equation to calculate mean condition factors from weight–length relationships is given as K_mean = 100aL^b?3. Relative weight W_rm = 100W/(a_mL^bm) can be used for comparing the condition of individuals across populations, where a_m is the geometric mean of a and b_m is the mean of b across all available weight–length relationships for a given species. Twelve recommendations for proper use and presentation of weight–length relationships, condition factors and relative weight are given.     

Charge density on native and ultraviolet-irradiated myosin A

The axial ratios (a/b) of native and 60 min. ultraviolet-irradiated myosin A molecules were calculated from previously reported sedimentation and diffusion data; values found were a/b = 74, a = 1880 A., and b = 26 A. for native myosin A; a/b = 104, a = 3280 A., and b = 32 A. for 60 min. ultraviolet-irradiated myosin A. Electrophoretic mobilities gave identical values of 3.2 (±0.1) × 10^?5 cm.²/v.-sec. for both native and 60 min. ultraviolet-irradiated myosin A. From the prior sedimentation and diffusion data, together with newly obtained electrophoretic data, the net charge Z and the charge density σ of native and ultraviolet-irradiated myosin A molecules were calculated from Henry's equation. The following results were obtained: for native myosin A, Z = 160 negative charges per molecule and σ = 22 coulombs/cm.²; for ultraviolet-irradiated myosin A, Z = 312 negative charges per molecule and σ = 20 coulombs/cm.². The results of this study provide an experimental demonstration that, the electrophoretic mobility of charged solute particles is dependent upon the particle charge density and not on the absolute charge of the particle.     

Length–weight relationships for selected fish species of Rio Trombetas Biological Reserve: a reference study for the Amazonian basin

Length–weight relationships (LWR) are presented for 27 freshwater fish species representing 11 families captured in the Trombetas River, a clearwater left margin tributary of the Amazon River. The allometry coefficient (b) of the LWR (W = aTL^b) ranged from 2.51 to 3.49, with a median value of 3.00. This study represents the first reference on LWR for 23 species and new records of maximum lengths for 15 species.     

Length–weight relationships of fish species in the freshwater rift valley lakes of Kenya

This study reports length–weight relationships for 10 species of fish encountered in the only two freshwater lakes wholly in the Rift Valley of Kenya, Naivasha and Baringo. In Lake Naivasha, none of the species analysed was native to the lake. Two were introduced species non‐native to East Africa (Micropterus salmoides, Cyprinus carpio), with three native to East Africa but not to the lake (Tilapia zillii, Oreochromis leucostictus, Barbus paludinosus). In Lake Baringo, all species were native (Oreochromis niloctictus baringoensis, Labeo cylindricus, Barbus intermedius autralis, Barbus lineomaculatus, Clarias gariepinus). Specimens were collected by gill netting in September 2004 and October 2005. With the exception of B. lineomaculatus, the b values in the relationship W = aL^b were between 2.90 and 3.22.     

Weight–length relationships of some fish species of the Iberian Peninsula

This study reports weight–length relationships (WLR) for Salmo trutta (Linnaeus, 1758), Phoxinus phoxinus (Linnaeus, 1758), Chondrostoma Chondrostoma miegii (Steindachner, 1866), Barbus graellsii (Steindachner, 1866), Barbatula barbatula (Linnaeus, 1758) and Gobio gobio (Linnaeus, 1758). Specimens were collected by electrofishing during summer between 1996 and 1998. The b values in the WLR W = aL^b varied between 2.97 and 3.42. To the best knowledge of the authors, this study presents the first reference on WLRs for four of the species in Spanish waters.     

Co-variation of gonadosomatic index and parameters of length–weight relationships of Mediterranean horse mackerel, Trachurus mediterraneus (Steindachner, 1868), in the eastern Adriatic Sea

Seasonal changes in length–weight relationships (LWRs), gonadosomatic index (GSI) and condition factor of Mediterranean horse mackerel, Trachurus mediterraneus (Steindachner, 1868), were studied. Ranging from 14.8 to 39.1 cm total length (TL), a total of 1245 specimens (605 males and 640 females) was collected in the eastern Adriatic Sea. Samples were taken at monthly intervals (January–December 2003) using bottom trawls. The b values of LWRs (W = aL^b) varied during the year with season and condition. Including specimens collected in all seasons, the b values showed that growth of both males and females was positively allometric, i.e. specimens changed shape as they gained weight. The GSI reached maximum values in June and a minimum in December. The condition factor was constant during the pre‐spawning period, lowest immediately after spawning (September), and highest at the end of the recovery phase (December).     

Length–weight relationships of four cavefish species from China

Length‐weight relationships (LWRs) were estimated for four cavefish species belonging to the genus Sinocyclocheilus (Cypriniformes: Cyprinidae) occurring in the Nanpanjiang River and Hongshuihe River, which constitute the upstream of the species, S. angularis, S. furcodorsalis, S. rhinocerous, and S. tileihornes, were collected from 2011 to 2017. The b values of LWRs of these four species ranged from 2.830 to 3.719 and the correlation coefficient values (R²) were high for all species. This is the first record of LWRs for cavefish species with the horn in FishBase database.     

Length–weight relationships for 47 coastal fish species from the northern Aegean Sea, Turkey

Length–weight relationships for 47 coastal fish species from Gökceada Island in the northern Aegean Sea, Turkey are presented. Samples were caught in depths of <30 m by gill and trammel nets between March 2004 and February 2005. The most abundant families were Sparidae (30%), Centracanthidae (19.9%), Serranidae (7.14%), Scorpaenidae (6.59%) and Labridae (6.09%). Estimates for parameter b of the length–weight relationship (W = aL^b) ranged between 2.08 and 3.73. The mean b‐value 3.03 ± 0.052 (SE) was not significantly different from 3. Significant differences between b‐values were found between sexes for Boops boops, Diplodus annularis, Mullus surmuletus, Pagellus acarne, Sarpa salpa, Spicara maena and Spicara smaris and between seasons for Diplodus annularis, Mullus surmuletus and Spicara maena.     

The species–area relationship derived from species-specific incidence functions

The species–area relationship (SAR), describing the increase in species number (S) with increasing area (A), is one of the most robust patterns in ecology with great significance for conservation. The SAR is generally formulated as a power function, S = kA^z, although the semilogarithmic form S = a + b log A has often been used by botanists. Here we unite the two forms by deriving SARs from the incidence functions of the species that make up the community. We show how the decisive scaling parameters z and b relate to the properties of individual species, and highlight why the biological interpretation of SARs has been so enigmatic.     

Age,growth and mortality of scaldfish (Arnoglossus laterna Walbaum, 1792) from the Adriatic Sea

The population dynamics parameters of scaldfish, Arnoglossus laterna, from the Adriatic Sea were studied. Specimens ranging from 4.5 to 17.1 cm in total length were collected from commercial bottom‐trawl catches (2000–2006). Spawning from April through the end of August with a peak in May, A. laterna is one of the non‐target species usually present in mixed bottom trawl catches. The overall male to female ratio was 1.00 : 0.61. The oldest individual was 6 years of age. Length–weight relationships showed positive allometric growth (b = 3.36 for males and b = 3.39 for females). Parameters of the von Bertalanffy growth equation were: L_∞ = 17.3 cm; K = 0.258 per year; t₀ = ?1.0026 year; R² = 0.925. The relatively low value of total mortality (Z = 0.90) and relatively high value of constant rate of natural mortality (M = 0.64) was estimated. Presumed calculated fishing mortality (F = 0.26) and the consequently estimated exploitation ratio (E = 0.29) indicated no danger of an over‐exploitation of this species in the study area at the current level of fishing pressure. The low T max and correspondingly high M suggest that this small benthic predator plays an important role in the Adriatic ecosystem as a prey species for large benthic predators. However, the estimates include uncertainties and require further confirmation, especially with regard to natural mortality.     

Length–weight relationship of six notothenioid species from sub‐Antarctic waters (Beagle Channel,Argentina)

This study presents length‐weight relationships (LWR) for six species of fishes of the Suborder Notothenioidei that inhabit the sub‐Antarctic waters of the Beagle Channel (Argentina). These species represent five of the nine families of this Suborder. The specimens belong to historical fish collections in the area (from 1987 to 1990) using gill and trammel nets. All species but Eleginops maclovinus had no previous LWR estimates. The coefficient of determination (r²) ranged from 0.91 to 0.99 and b values ranged from 2.74 to 3.2. Harpagifer bispinis was the only species with a b value lower than three. This information is useful to predict the weight from the length data and to provide insights into the ecology of sub‐Antarctic nototheniod fish.