Habitat-Specific Density and Diet of Rapidly Expanding Invasive Red Lionfish,Pterois volitans,Populations in the Northern Gulf of Mexico

Invasive Indo-Pacific red lionfish, Pterois volitans, were first reported in the northern Gulf of Mexico (nGOM) in summer 2010. To examine potential impacts on native reef fish communities, lionfish density and size distributions were estimated from fall 2010 to fall 2013 with a remotely operated vehicle at natural (n = 16) and artificial (n = 22) reef sites. Lionfish (n = 934) also were sampled via spearfishing to examine effects of habitat type, season, and fish size on their diet and trophic ecology. There was an exponential increase in lionfish density at both natural and artificial reefs over the study period. By fall 2013, mean lionfish density at artificial reefs (14.7 fish 100 m⁻²) was two orders of magnitude higher than at natural reefs (0.49 fish 100 m⁻²), and already was among the highest reported in the western Atlantic. Lionfish diet was significantly different among habitats, seasons, and size classes, with smaller (<250 mm total length) fish consuming more benthic invertebrates and the diet of lionfish sampled from artificial reefs being composed predominantly of non-reef associated prey. The ontogenetic shift in lionfish feeding ecology was consistent with δ¹⁵N values of white muscle tissue that were positively related to total length. Overall, diet results indicate lionfish are generalist mesopredators in the nGOM that become more piscivorous at larger size. However, lionfish diet was much more varied at artificial reef sites where they clearly were foraging on open substrates away from reef structure. These results have important implications for tracking the lionfish invasion in the nGOM, as well as estimating potential direct and indirect impacts on native reef fish communities in this region.     

Length‐weight relationship of Pseudophoxinus alii Küçük,in Lake Yamansaz,a coastal freshwater lake in Antalya,Turkey

This study describes the length–weight relationship (LWR) of Pseudophoxinus alii from the Yamansaz Lake, a coastal freshwater lake in Antalya, Turkey. A total of 105 specimens were obtained using a variety of nets between April 2007 and March 2008. Total lengths ranged from 3.4 to 14.3 cm. The length–weight relationship showed a positive allometric growth (b = 3.012; R² = 0.988). The study presents the first reference on LWR for this threatened species. The results also indicate a new maximum total length not previously reported in the international literature.     

Length‐weight and length‐length relationships of the genus Alosa (Clupeoidei: Clupeiformes: Clupeidae) along the southern Caspian Sea coast

Length–weight (LWR) and length–length (LLR) relationships were estimated for four shad species of the genus Alosa, reported from along the southern Caspian Sea coast, north of Iran in a study from March 2014. Two of these species are endemic to the Caspian Sea. The length–weight parameter b for these species ranged from 2.99 to 3.24, with regression coefficients (r²) ranging from 0.91 to 0.99. All LLRs were highly significant (r² > 0.96).     

Real‐time PCR quantification of Bemisia tabaci (Homoptera: Aleyrodidae) B‐biotype remains in predator guts

The cotton whitefly, Bemisia tabaci (Gennadius) B‐biotype, is fed on by a wide variety of generalist predators, but there is little information on these predator–prey interactions, especially under field conditions. In this study, a real‐time polymerase chain reaction (PCR) assay was developed to quantify B. tabaci B‐biotype remains in predator gut. The B. tabaci B‐biotype genomic DNA copy number was referred to the actual amount of BT1 isolate, the B. tabaci B‐biotype specific DNA fragment. The numbers of BT1 isolate in one B. tabaci B‐biotype egg, individual adult and a single red‐eyed nymph were 2.56 × 10³, 2.56 × 10⁴, and 1.29 × 10⁴ copies, respectively. When Propylaea japonica adults fed on one, two, four, eight or 16 red‐eyed nymphs, the detected numbers of BT1 isolate ranged from 2.77 × 10⁴ to 4.05 × 10⁵ copies, forming a strong linear relationship (R² = 0.9899). Following the consumption of two red‐eyed nymphs, prey DNA was detectable in 100% of P. japonica at t = 0, decreasing to 80.0% and 60.0% after 1–4 h and 8 h of digestion, respectively, with 3.36 × 10⁴–1.25 × 10³ BT1 isolate copies. The predation by field‐collected predators, 26 larvae of P. japonica, and of Harmonia axyridis each, Chrysopa spp. larvae (Chrysopa pallens and C. formosa, 18 individuals in total), and a single adult of Scymnus hoffmanni, 19 adults of Orius sauteri and nine adult spiders (Erigonnidium graminicolum and Neoscona doenitzi), on B. tabaci B‐biotype were quantified. Of the 99 analysed predator individuals, 3.65 × 10²–4.60 × 10⁵ copies of BT1 isolate, equivalent to 0.8–18.8 red‐eyed nymphs were detected. These results suggest that TaqMan real‐time PCR technology may provide a rapid and sensitive method for quantifying B. tabaci B‐biotype remains in predator guts and will be invaluable in assessing the food web relationship between prey and arthropod predators.     

Length‐weight and length–length relationships of three algae‐scraping cyprinid species from Iran

The study presents length–weight relationships (LWRs) and length–length relationships (LLRs) for three algae‐scraper species; Capoeta coadi from the Kouhrang River (Iran; 32°23′N, 50°08′E) a part of the Tigris drainage basin, Capoeta pyragyi from Cheshmeh Langan River (32°55′N, 50°10′E) a part of Zayanderud River basin and Capoeta umbla from Chooman River (35°57′N, 45°47′E). Fish were sampled by electro fishing (Samus1000; Power Out: 200 watts) in August, September and October 2017. Sampling was carried out each months in sites covering an area of about 100 m² including runs, riffles and pools at a water depth of 10–60 cm. The obtained LWRs and LLRs showed a high level of correlation (r² > 0.99).     

Length‐weight relationships of four fish species from Visakhapatnam coast,India

Length‐weight relationships (LWRs) were determined for 4 deep water fish species from Visakhapatnam coast, India. Specimens were collected fortnightly between December 2013 and November 2015 from commercial trawls at Visakhapatnam fish landing centre (16.98°N–20.2°N, Long.82.19°–86.53°E). Individuals were captured between 100 and 300 m depth with shrimp trawl net (head rope length: 37–46 m and cod end mesh size: 30–40 mm). Total length (TL) (nearest to 0.1 cm) and body weights (nearest to 0.1 g) were taken each individual. All LWRs were significant with r² values ranged from 0.958 for Uranoscopus bicinctus Temminkc & Schlegel, 1843 to 0.983 for Uranoscopus chinensis Guichenot, 1882 and “b” values ranged from 2.832 for U. bicinctus to 3. 402 Synodus indicus (Day, 1873).This study provides a new maximum length data for three species (Uranoscopus bicinctus Temminkc & Schlegel, 1843; Uranoscopus chinensis Guichenot, 1882 and Uranoscopus marmoratus Cuvier, 1829).     

Length‐weight and length‐length relationships of thirteen fish species from the lower Jinsha River,southwest China

Length‐weight and length‐length relationships were investigated for 13 freshwater fish species from the lower Jinsha River, southwest China (from 101°32′49.63″E; 26°35′38.27″N to 104°37′48.14″E; 28°45′59.55″N). Fish were sampled from five sites during 2014 and 2016, using trap‐nets, gillnets (major mesh size: 2–6 cm), longline and electrofishing. Length‐weight relationships for six and length‐length relationships for 12 species are the first report to FishBase, respectively. Moreover, new maximum length for 11 species are also presented to FishBase in this study. All regressions were highly significant (p < .001), with the coefficient of determination r² > .950. These information will be helpful for management and conservation in local fishes and fisheries.     

Length‐weight and length‐length relationships of four small fishes from the Atrai River,Dinajpur, Bangladesh

Length‐weight (LWRs) and length‐length relationships (LLRs) were determined for four fish species collected from the Atari River in Dinajpur of Bangladesh. Sampling took place monthly between January and June 2016, using seine nets of commercial fishermen (mesh size 4 mm). In LWRs (r² > .927, p < .05), slope (b) was estimated as 3.191, 2.992, 3.217 and 3.109 for Acanthocobitis botia, Botia lohachata, Canthophrys gongota and Chanda nama, respectively. In LLRs (r² > .812, p < .05), lengths i.e. TL, SL, HL and FL were highly correlated. The present study on these species would be the baseline for FishBase dataset.     

Length‐weight relationships of 10 coastal fish species from the Visakhapatnam coast,India

We analysed the length‐weight relations (LWRs) of 10 fish species inhabiting different habitats from Visakhapatnam, Coast of India. Samples were obtained between August 2013 and December 2016 from commercial trawlers at the local fish landing centre (16.98°N–20.20°N, Long.82.19°–86.53°E). Fishes were captured between 100 and 300 m depth with demersal trawl net (head rope length: 46 m and cod end mesh size: 40 mm with a 38 m high speed. Total length (TL; nearest to 0.1 cm) and body weights (nearest to 0.1 g) were taken from each individual. This study provides new maximum length data for two species (Archamia bleekeri (Günther, 1859) and Ostorhinchus fleurieu (Lacepède, 1802), and LWR estimates for rare deep reef associated fishes are provided for the first time. All LWRs were significant with r² values ranging from .908 for Sargocentron praslin (Lacepède, 1802) to .981 for Parapercis pulchella (Temminck & Schlegel, 1843) and “b” values ranged from 2.5216 for Parapercis pulchella (Temminck & Schlegel, 1843) to 3.4746 for Ostorhinchus fleurieu Lacepède, 1802.     

Length–weight and length–length relationships of two goby species,Neogobius caspius (Eichwald, 1831) and Proterorhinus nasalis (De Filippi, 1863) from the southern Caspian Sea

The present study provides the length–weight (LW) and length–length (LL) relationships for two goby species, Neogobius caspius and Proterorhinus nasalis, which were captured in the southern Caspian Sea. Total length (TL) and standard length (SL) were determined as well as weight. Specimens were collected monthly from September 2014 to August 2015 by beach seine (mesh size 10 mm). The LW parameter b for these species was 3.17 and 2.99, respectively, with a high coefficient of determination (r² > .95). All LLRs were highly correlated (r² > .97). Both species had no previous LWR and LLR estimates in FishBase.     

Length–weight and length–length relationships of seven freshwater fish species from the Daning River,a tributary of the Yangtze River,southwest China

This study determined the length–weight relationships (LWRs) and length–length relationships (LLRs) of seven freshwater fish from the Daning River, a tributary of the Yangtze River, southwest China. Specimens were collected between July 2016 and July 2017 using drift gill nets (mesh size 1, 2 and 3 cm), cage net (0.5 cm mesh size) and electroshock fishing techniques quaterly. Parameter b values of LWRs ranged from 2.647 to 3.276 (r² > .963) and b values of LLRs ranged from 1.091 to 1.213(r² > .985). Six new LLRs and seven new maximum length data are presented. The biometric data and their relationships are relevant to Fishers science to supplement other data sets needed for fisheries management.     

Length–weight and length–length relationships of four fish species from the middle reaches of the Minjiang River,southwest China

Length–weight (LWR) and length–length (LLR) relationships are reported for Glyptothorax fokiensis (Rendahl, 1925), Microphysogobio kachekensis (Oshima, 1926), Pseudobagrus brevicaudatus (Wu, 1930), and Sinibrama taeniatus (Nichols, 1941) from the middle reaches of the Minjiang River and its tributaries, Sichuan Province, in southwest China. A total of 675 specimens were obtained between 2013 and 2016 using various types of fishing gear and electroshock fishing techniques. Standard length and total length for each individual were measured by digital slide caliper and each body weight was taken by digital balance. The b‐values for LWRs varied from 2.617 to 3.249 (r² > .954), and the LLRs were highly correlated (r² > .983; p < .01).     

Diet of farm‐escaped sturgeon in the Yangtze River

The diet of farm‐escaped sturgeon accidentally introduced into the Yangtze River ecosystem was investigated from samples collected over 10 days. The fish had consumed adequate quantities of natural food, with prey type related to fish body size. The fish were categorized according to their primary dietary component: demersal fish were most common prey of kaluga Huso dauricus and H. dauricus × Acipenser schrenckii hybrids of total length 120.3–188.7 cm. Shrimp Macrobrachium nipponensis made up the major portion of the diet of H. dauricus × A. schrenckii and Acipenser baerii × A. schrenckii of total length 91.1–106.8 cm. Gammarid amphipods were consumed by A. baerii × A. schrenckii of total length 35.0–81.2 cm. The body length of prey was proportional to the fork length of the sturgeon, Y = 0.19X‐9.46, R² = 0.997. Escaped sturgeon had travelled at least 898 km downstream from the point of escape in the Yangtze River and were feeding on native macrobenthos and demersal fish.     

Length–weight relationship and condition factor of the Characidae matrinxã, Brycon falcatus (Müller & Troschel, 1844), in the Teles Pires River,southern Amazon

The aim of this study was to verify whether the in situ supply of soybean as a fish attractant bears any influence on the length–weight relationship and condition factor of the omnivorous fish species, Brycon falcatus. In addition, estimated was the length–weight relationship, standard and total length, condition factor, and size of B. falcatus in the spawning period in the Teles Pires River Basin. In the experimental design, rivers of the Teles Pires Basin containing soybean attractant (Verde River, Celeste River, Teles Pires River and the Tapaiuna River) were mapped. Fish were also collected from the Cristalino River, which contained no soybean attractant (treatment control). Samples were collected from August 2012 to July 2013. Length–weight relationship of B. falcatus in the Teles Pires River Basin can be obtained by the expression: Wt = 0.0091*SL^3.376, r² = .97, n = 102, and length‐length relationship: TL = 1.128*SL + 3.978, r² = .96. The condition factor of all specimens collected in the Teles Pires Basin was k = 1.055. Size at capable phase (L50) of spawning was estimated at 23 cm standard length. Results showed no significant difference in the length–weight relationship or condition factor of B. falcatus collected from rivers with or without soybean attractant. Concluded is that the in situ supply of soybean as a fish attractant does not interfere with the wellbeing of B. Falcatus in the Teles Pires River Basin.     

Length–weight and length–length relationships of five Mystus species from the Ganges and Rupsha rivers,Bangladesh

This study focused on the length–weight and length–length relationships of five Mystus species from Bangladesh. A sum of 398 individuals (Mystus bleekeri = 47, Mystus cavasius = 171, Mystus gulio = 59, Mystus tengra = 65, and Mystus vittatus = 56) was collected from the Ganges and Rupsha rivers, Bangladesh. Fishes were caught by gill net (mesh sizes: 2.0–4.0 cm) and cast net (mesh sizes: 1.5–3.0 cm) from July 2014 to June 2015. Total length (TL), fork length (FL) and standard length (SL) were measured to 0.1 cm, while whole body weight (W) was taken to the nearest 0.1 g for each individual. The TL ranged from 6.0–13.5 cm for M. bleekeri, 5.0–15.0 cm for M. cavasius, 7.4–17.2 cm for M. gulio, 4.6–11.6 cm for M. tengra and 5.5–12.3 cm for M. vittatus. The W varied from 3.0–18.2 g for M. bleekeri, 1.3–30.4 g for M. cavasius, 6.1–62.2 g for M. gulio, 1.7–15.1 g for M. tengra and 2.7–19.2 g for M. vittatus. All LWRs were highly significant (p < .001), with all r² values ≥.950. The LLRs were also highly significant (p < .001), with all r² ≥.980. This study provides information on LWRs and LLRs for M. gulio and M. tengra for the first time. The results of this study can be very effective for stock assessment of Mystus species in the Ganges and Rupsha rivers as well as in the surrounding ecosystems.     

Length–weight and length–length relationships of three Blenny species from the Persian Gulf and the Gulf of Oman

The present study provides the length–weight and length–length relationships information (LWR & LLR) for three Blenny species; Antennablennius adenensis from the coast of Larak Island in the Persian Gulf and Istiblennius pox and Omobranchus mekranensis, which were captured in the coasts of Chabahar city in the Gulf of Oman, Iran. Total length (TL) and standard length (SL) were determined as well as weight. Specimens were collected occasionally in summer 2017 and winter 2018 by Hand net. The length–weight parameter b for these species was 2.84, 3.29 and 3.06 respectively with a high coefficient of determination (r² ≥ 0.95). All LLRs were highly correlated (r² > 0.99). All three species had no previous report for LWR and LLR estimates in FishBase.     

Length–weight and Length‐length relations of four fish species from the Chilika Lake,East coast of India

This study reports the length–weight relationship (LWR) and length‐length relationship (LLR) estimated for four fish species inhabiting in Chilika Lake, India. Total 504 specimens were sampled from mono‐filament gill nets (mesh size 12 mm, 22–24 mm, 34–38 mm, 42 mm) during January 2015 to December 2015. The estimated b values from LWR ranged between 2.79 (T. biaculeatus) to 3.29 (C. praeustus). In all species, the relationships between length‐weight and length‐length were highly correlated (p < .05). The study provides first world reports on LWRs and LLRs for all the 4 studied species.     

Length‐weight relationships,condition factor,gonadosomatic index‐based size at first sexual maturity,spawning season and fecundity of Aspidoparia morar (Cyprinidae) in the Jamuna River (Brahmaputra River distributary), northern Bangladesh

The present study describes the length‐weight relationships (LWRs), length‐length relationships (LLRs), Fulton's condition factor (K_F), size at first sexual maturity, spawning season, sex ratio and fecundity of the Morari Aspidoparia morar (Hamilton, 1822) (Cyprinidae). Sampling was done using traditional fishing gear jhaki jal (cast net) from July 2010 to June 2011. Total length (TL), fork length (FL) and standard length (SL) were measured with digital slide calipers. Individual body weight (BW) and gonad weight (GW) were determined to an accuracy of 0.01 g for all specimens. The gonadosomatic index (GSI) was calculated and size at first maturity for males and females estimated using GSI and TL as indicators. Female ≥ size at first maturity was used to determine fecundity. A total of 1200 specimens (males = 552, females = 648) ranging from 4.06–12.84 cm TL and 0.53–16.75 g BW were analyzed. The overall coefficient b for the LWR indicated positive allometric growth (>3.00) in males and isometric growth in females (~ 3.00). ancova (analysis of covariance) revealed significant differences between males and females (P < 0.001). All LLRs were highly correlated (r² > 0.973, P < 0.001). Sizes at first sexual maturity for males and females were 6.0 and 7.0 cm TL, respectively. K_F changed little throughout the year and GSI peaked in November to April, indicating the spawning season (GSImax = 15.0 in females, 2.0 in males). Mature females were dominant during the entire spawning season except in April. Mean total fecundity was 6700 ± 3500, ranging from 1860 to 19680. In addition, relative fecundity ranged from 190 to 1200 (mean 560 ± 235) in the Jamuna River. To ensure sustainable management of this species, the protection of mature individuals during the peak spawning season is highly recommended.     

Length‐weight relationships of five Triplophysa species from the northwest of China

Length‐weight relationships were estimated for five Triplophysa species from the northwest China. A total of 1,598 specimens were collected using set gillnets (mesh size 1.5 cm) and ground bamboo cages in May 2012, and August 2014. This study presents the first references on LWRs for Triplophysa minuta, T. siluroides, and T. tenuis, and two new maximum length records for T. yarkandensis and T. strauchii. Statistical length–weight relationships for all five species were highly significant (p < .001), with R² values >.915.     

Length–weight and length–length relationships of five fish species in the Atrai River,Dinajpur, Bangladesh

A total of 502 specimens were obtained during monthly samplings from July to December 2015, by fishermen using seine nets, gillnets and cast nets. Length–weight (LWRs) and length–length (LLRs) relationships were estimated for five fish species collected from the Atrai River in the northwestern region of Bangladesh. The values of slope (b) in LWRs (r² > .913, p < .001) were determined as 2.899 for Aspidoparia jaya, 3.059 for Gagata cenia, 3.004 for Gagata youssoufi, 2.755 for Salmophasia bacaila, and 3.222 for Salmophasia phulo, respectively. The linear relationships in TL, FL and SL were highly correlated (for all cases: r² > .897, p < .001). No previous information on LWRs (except for G. cenia) and LLRs (except for S. bacaila) of these selected species were found in FishBase.