Influence of environment upon the life history of gudgeon, Gobio gobio (L.): a recent and successful colonizer of the Iberian Peninsula

The growth and the reproductive tactics of gudgeon, Gobio gobio (L.) were assessed in three contrasting streams of the Iberian Peninsula: the Rivers Moros and Ucero, tributaries of the R. Duero, and the R. MatarrańGa, a tributary of the R. Ebro. The R. Duero gudgeon have spread in the last 50 years while their presence in the lower tributaries of the R. Ebro followed the construction of reservoirs in the mid 1960s. The life histories of the Moros and MatarrańnGa gudgeon are very similar; rapid growth in spring, early reproduction (1 -year-old), high reproductive cost, short life-span and trend to semelparity. Both populations are strongly influenced by the severe summer droughts that result in (I) reduction in the condition coefficient, (2) reduction in the growth rate (particularly in the River MatarrańGa), (3) single spawning and (4) no gonad development in the summer. The gudgeon in the Ucero delay maturity, grow slower, are multi-spawners and have a longer life span. All the Duero populations come from the same genetic pool and they are actually connected through the populations living along this river basin, whereas the MatarrańGa population is not genetically linked, we hypothesize that the differences between these populations are environmentally induced.     

Age, growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains

Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50% sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size.     

Reproductive biology of Hemiramphus brasiliensis and H. balao (hemiramphidae): maturation,spawning frequency,and fecundity

Analyses of life-history data show that both the size-specific batch fecundities and the age-specific spawning frequencies differ for two halfbeak species, Hemiramphus brasiliensis, the ballyhoo, and H. balao, the balao. Halfbeak ages were determined from sectioned otoliths; histological data was used to describe oocyte development and estimate spawning frequency; and batch fecundity was measured from counts of whole oocytes in final maturation. Hemiramphus brasiliensis lived longer (4 versus 2 years) and had a higher survival rate (14.9% versus 7.5% annually) than H. balao did. Of the two species the larger and longer-lived congener, H. brasiliensis, reached sexual maturity at a larger size (fork length 198 versus 160 mm). The spawning period of age-0 females was strongly related to season, whereas spawning by older females occurred throughout the year. Reproduction by both species peaked during late spring or early summer, and all mature females were spawning daily during April (H. brasiliensis) or June (H. balao). This is the first demonstration of iteroparity for the family Hemiramphidae. H. brasiliensis had a lower batch fecundity (about 1164 versus 3743 hydrated oocytes for a 100-g female) than H. balao did. Such low batch fecundities are typical of the order Beloniformes, but quite different from those of other fishes that live in association with coral reef habitats. H. balao's higher batch fecundity is consistent with the life-history theory that predicts higher numbers of eggs for shorter-lived species; this is possible because H. balao produces smaller hydrated oocytes than H. brasiliensis (modal diameter about 1.6 versus 2.4 mm). The high spawning frequency of Hemiramphus species compensates for their low batch fecundity. The annual fecundity of both species is similar to that of other reef fish species, after adjusting for body size and spawning frequency. The lifetime fecundity of H. balao was very similar to that of H. brasiliensis, after accounting for the differences in survival for each species. This suggests a fine tuning of different reproductive traits over the entire life cycle that results in roughly equivalent lifetime fecundity for both species.     

Life-history traits of the endangered river blenny Salaria fluviatilis (Asso) and their implications for conservation

The life-history characteristics of the river blenny Salaria fluviatilis in a Mediterranean stream in north-east Spain have been studied. The maximum age observed was 4+ years in both sexes, although only age groups 0+ and 1+ years were well represented. For both sexes, growth was rapid between April and June (before the summer drought) and in October. The instantaneous rate of monthly growth (April to October) was positively correlated with water depth. All fish attained sexual maturity during their first year of life. Females spawned multiple times. Spawning occurred mainly from June to August, although older females (2+ years old) began in May. The relationship between fecundity and total length recorded for older females in the spring was not significantly different from that obtained for 1 year-old females in the summer. The mean diameter of ripe oocytes, however, was greater in older females. Larger eggs that were laid during a period of good food supply (spring) might have a higher probability of survival. The results suggest that female fecundity is affected by environmental conditions. The species is characterized by fast growth, early maturity, multiple spawning and limited longevity. This may be a good life-history strategy for small fish species in unstable environments, where adult mortality is high, variable or unpredictable. Some life-history traits of the river blenny suggest that this species might be vulnerable to more severe drought conditions than those associated with the Mediterranean climate.     

Observations on the age, growth, reproduction and food of the roach Rutilus rutilus (L.) in two rivers in southern England

Scales and opercular bones from 632 roach from the River Stour were used for age and back-calculated growth determinations. The scales had clearer inner annuli but operculars clearer outer annuli in fish more than nine years old. The annuli were laid in late May or early June at the beginning of the growth period. Growth was minimal between November and April. Roach from both rivers grow faster than those in most other European waters. Female roach grow faster than males; River Frome roach faster than those from the Stour. Spawning occurred in May and elaboration of gonads between September and May. Immature roach have an annual cycle in condition with a maximum in June and a minimum in early Spring. The condition of mature females is affected by the gonad cycle. The fecundity of Stour roach is represented by the formula: log egg number=4.43 log length (mm)—1.69. Approximately half of the Stour males attained sexual maturity at age III and most of the rest by age IV. Half of the females were mature at age IV and the remainder by age V. Both brood success and growth rate varied from year to year but independently of one another. Most Stour roach ate aquatic insect larvae and molluscs but algae were more frequent in the diet of larger fish.     

Life-history strategies of Acrossocheilus fasciatus (Barbinae, Cyprinidae) in the Huishui Stream of the Qingyi watershed, China

Life-history traits of Acrossocheilus fasciatus were examined using 384 specimens collected monthly during May 2009 and April 2010 in the Huishui Stream of the Qingyi watershed, China. Using scales for age determination, female and male fish comprised five and four age groups, respectively. The monthly changes in marginal increment ratio suggested that annuli on scales were formed during March through May. Total lengths back-calculated significantly increased with age for both sexes and varied significantly between the two sexes at each age. The fact that females had larger body size and grew faster than males indicated the sexual size dimorphism for this species. Both sexes got their 50% maturity at age 3, when females and males were 105.3 and 112.1?mm total length, respectively. Based on the monthly changes in the gonado-somatic index and egg-development process, fish spawned from April through August. Absolute fecundity ranged from 295 to 3,573 eggs per fish and increased significantly with age. But relative fecundity, ranging from 11.77 to 69.96?eggs/g, was not significantly different among age groups. Compared with the life-history traits of an upstream population in the Puxi Stream (a headwater stream within this study watershed), the downstream population of A. fasciatus in the Huishui Stream (a 4th-order stream) exhibits larger body size, faster somatic growth, later sexual maturity, and lower reproductive investment. These variations in life-history strategies between the two populations could perhaps be explained by the spatial heterogeneity in habitat environment along the upstream–downstream gradient in this watershed.     

Life-history phenotypes in populations of Brachyrhaphis episcopi (Poeciliidae) with different predator communities

Variation among populations in extrinsic mortality schedules selects for different patterns of investment in key life-history traits. We compared life-history phenotypes among 12 populations of the live-bearing fish Brachyrhaphis episcopi. Five populations co-occurred with predatory fish large enough to prey upon adults, while the other seven populations lacked these predators. At sites with large predatory fish, both sexes reached maturity at a smaller size. Females of small to average length that co-occurred with predators had higher fecundity and greater reproductive allotment than those from populations that lacked predators, but the fecundity and reproductive allotment of females one standard deviation larger than mean body length did not differ among sites. In populations with large predatory fish, offspring mass was significantly reduced. In each population, fecundity, offspring size and reproductive allotment increased with female body size. When controlling for maternal size, offspring mass and number were significantly negatively correlated, indicating a phenotypic trade-off. This trade-off was non-linear, however, because reproductive allotment still increased with brood size after controlling for maternal size. Similar differences in life-history phenotypes among populations with and without large aquatic predators have been reported for Brachyrhaphis rhabdophora in Costa Rica and Poecilia reticulata (a guppy) in Trinidad. This may represent a convergent adaptation in life-history strategies attributable to predator-mediated effects or environmental correlates of predator presence.     

Enhancing knowledge on low-value fishing species: the distinct reproductive strategy of two gurnard species

The depletion and overexploitation of several fish stock demands for a valorisation of non-target and discarded species. Nonetheless, such species are often poorly studied, and information on their biological parameters must be gathered for effective population management. For 1 year, the reproductive strategy of the piper gurnard Trigla lyra and the red gurnard Chelidonichthys cuculus was studied by monthly samples obtained from commercial boats operating on western Portuguese coast. Both species showed a biased sex ratio towards females, especially for larger length classes. Length at first maturity could be estimated only for red gurnard (22.1 and 19.9 cm for females and males, respectively) because all piper gurnard individuals caught were mature. Piper gurnard showed determinate fecundity and a short spawning season, from November to February with a peak in January, whereas red gurnard showed indeterminate fecundity and a wide spawning season, from late December to May. The relative annual fecundity estimated for red gurnard (1893 ± 728 oocytes × g⁻¹ eviscerated weight [EW]) was higher than the one estimated for piper gurnard (1018 ± 250 oocytes×g⁻¹ EW). Although important information for understanding the species dynamics is presented in this study, additional information on other life-history parameters and of species landings is required.     

The life-history traits of widespread freshwater fish species: the case of Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) in water bodies at the southern limits of distribution

The Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) is a widespread Eurasian cyprinid freshwater fish. Although numerous studies have investigated the species’ life history traits across its main native range of distribution, little is known from water bodies located beyond the southern limits of the latter, especially where the species has been introduced. Between July 2010 and April 2011, a total of 949 R. rutilus specimens was collected from Porsuk Reservoir (NW Turkey), and life-history traits of age, growth, fecundity and egg size were studied and compared to six other R. rutilus populations (including Caspian Roach R. r. caspicus) from the southern limits of distribution. The Porsuk population was characterised by relatively shorter lifespan, slower growth and lower fecundity. These findings support previous studies emphasising the importance of local environmental factors in shaping the life-history traits of widespread fish species. These must be taken into consideration especially in view of the potential value of R. rutilus as an economic resource for in-land fisheries.     

Maturation,growth and fecundity of Arctic charr, <Emphasis Type="Italic">Salvelinus alpinus</Emphasis> (L.), life-history variants co-existing in lake systems of Southern Baffin Island,Nunavut, Canada

Two life-history variants of Arctic charr (Salvelinus alpinus), anadromous and lake-resident, have been previously identified in lakes of Southern Baffin Island, Nunavut, Canada. In accordance with classical life-history theory, it is hypothesised that anadromous charr will delay maturation in both size and age, and have increased fecundity (per spawning event) in comparison with lake-resident charr. Sagittal otoliths and biological data were collected for both life-history variants within the three studied lakes: Iqalugaarjuit, Qasigiat and Qinngu. Sagittal otoliths were embedded in epoxy resin, cross-sectioned for age determination, and imaged for back-calculation (size and age). Back-calculated data in each lake were fit to von Bertalanffy growth models for each life-history variant and compared via analysis of residual sums of squares. Anadromous charr had greater mean size at maturity and experienced a delay in mean age at maturity in comparison with lake-residents. The relationship between size and fecundity or egg diameter did not differ between the two life-history variants. Growth models indicate that the overall growth coefficients of lake-resident and anadromous charr were different in all three studied lakes. The Brody growth coefficient for all lake-resident charr populations was greater than anadromous individuals indicating that maximum length was reached at a rapid rate, resulting in a smaller asymptotic length. Indirect evidence suggests that anadromous and lake-resident charr belong to one reproductive population. Future genetic analysis is necessary to further determine the degree of divergence between the life-history variants.     

Variations in the spawning periodicity of eight fish species in three English lowland rivers over a 6 year period, inferred from 0+ year fish length distributions

The spawning periodicity of eight fish species was investigated in three English lowland rivers over a 6 year period from patterns in 0+ year fish standard length ( L _S) distributions. A single cohort of 0+ year dace Leuciscus leuciscus , roach Rutilus rutilus and perch Perca fluviatilis was observed each year, suggesting that these species spawned only once annually. By contrast, populations of chub Leuciscus cephalus , bleak Alburnus alburnus , bream Abramis brama , gudgeon Gobio gobio and minnow Phoxinus phoxinus were inferred to spawn on more than one occasion each year. Annual and intercatchment variations occurred in the L _S distribution patterns of some of the fish species. In chub, for example, although a minimum of two 0+ year cohorts occurred in all years in the River Trent, 'multiple' spawning (either at the individual or population level) was most apparent in 1999, 2003 and 2004. By contrast, 'multiple' spawning events were not evident in all years in the Warwickshire Avon and Yorkshire Ouse, with recruitment presumably based upon a single spawning event in some years. There is effectively a trade-off between early spawning (extended growing season), and the possibility that environmental conditions will impact upon recruitment success, and the potential for reduced overwinter survival of smaller individuals with lower lipid resources from later spawning events. Notwithstanding, fishes as small as 15 mm L _S survived the winter in some years, suggesting that progeny from later spawning events may make important contributions to fish recruitment success.     

Life-history Patterns of 25 species from European Freshwater Fish Communities

Fish life-history patterns were evaluated in relation to the trilateral continuum model by analyzing data from 25 species inhabiting European freshwaters. Multivariate tests identified a trend between later-maturing fishes with higher fecundity, larger size, and few spawning bouts per year and the opposite suite of traits with small fishes. A second trend contrasted fishes having parental care, smaller eggs, and longer breeding seasons against fishes with the opposite suite of traits. As a result, two extreme life-history patterns could be identified among European freshwater fish species: opportunistic and periodic. Nevertheless, intermediate patterns were also present. A true equilibrium life-history pattern was not represented among 25 fish species from European freshwaters. The high concordance of basic life-history patterns among distantly related taxa is probably caused by some universal trade-offs among life-history variables. As a consequence, only a limited life-history patterns may be recognizable among fish species, independently of the origin of fish communities.     

A meta‐analysis of latitudinal variations in life‐history traits of roach,Rutilus rutilus,over its geographical range: linear or non‐linear relationships?

1. We collated information from the literature on life history traits of the roach (a generalist freshwater fish), and analysed variation in absolute fecundity, von Bertalanffy parameters, and reproductive lifespan in relation to latitude, using both linear and non-linear regression models. We hypothesized that because most life history traits are dependent on growth rate, and growth rate is non-linearly related with temperature, it was likely that when analysed over the whole distribution range of roach, variation in key life history traits would show non-linear patterns with latitude.
2. As fecundity depends strongly on length, and the length structure of females varied among populations, latitudinal patterns in fecundity were examined based on residuals from the length–fecundity relationship. The reproductive lifespan of roach was estimated as the difference between age at maturity and maximum age of females in each population.
3. The three life history traits of roach analysed all varied among populations and were non-linearly related to latitude. Only the relationship between reproductive lifespan and latitude was a better fit to a linear that to a quadratic model, although Loess smoothing curves revealed that this relationship was actually closer to biphasic than linear in form. A latitude of 50°N formed a break point in all three life history traits.
4. The negative relationships we have described between (i) fecundity and reproductive lifespan and (ii) fecundity and egg mass suggest that lower fecundity is compensated for by longer lifespan, while lower fecundity is compensated for by an increased egg mass, when analysed independently of location.     

The cause of extreme year class variation in a population of roach, Rutilus rutilus L., from a eutrophic lake in southern England

Investigations into the biology of the roach population at Slapton Ley, Devon, U.K. were carried out between October 1982 and December 1984 and data collected from the lake since 1977 have been re-analysed to assist interpretation. The roach population has been characterized in recent years by extreme year class variation and a tendency for year classes to alternate in strength. The survival of the roach was very poor, and the spawning population therefore consisted largely of 2-and some 3-year-old fish. Consequently, the size of the spawning stock was small and dependent on the strengths of the year classes that it contained. Recruitment to many year classes was probably limited by the size of the spawning stock. The occurrence of a poor year class in the population would therefore set up an autonomous cycle of poor recruitment to alternate year classes in a manner similar to many tropical marine fisheries. Observation of other British roach populations showed that a short life-span may be associated with conditions that promote very rapid growth rates. The growth rate of individual roach at Slapton was found to be one of the fastest in Britain, and this was apparently due to the very high productivity of Slapton Ley together with the persistence of the roach population at very low densities.     

Reproductive biology of the endangered Oxleyan pygmy perch Nannoperca oxleyana Whitley

The reproductive biology of the Oxleyan pygmy perch Nannoperca oxleyana is described from simultaneous studies of wild populations in north-eastern New South Wales and mature fish held in aquaria. In the wild, 50% of males and females matured at total lengths of 24·0–25·9 and 28·0–29·9 mm, respectively. The species displays sexual dichromatism during the spawning season, with males developing more intense red and brown fin and body colouration, and black pelvic fins. Captive male broodfish displayed territoriality during the breeding season, closely guarding sites within artificial, plant-like substrata in which pairs of fish spawned adhesive eggs. Protracted serial spawning of wild and captive fish occurred from September to April and May at mean water temperatures ≥16·6° C and day length ≥10·7 h. Captive broodfish spawned on an average of 57% of days during the 256 day spawning period. Gonado-somatic indices averaged 0·7% for all ripe males and 4·1–4·2% for all ripe females collected. Mean total and batch fecundities of captive females were 1323 eggs per fish and 7·8 eggs per fish per day, respectively, and relative fecundity was 587 eggs g⁻¹ of body mass. Batch fecundity of wild females was estimated at 7·8 eggs per fish. The adaptive significance of this reproductive strategy in a harsh, variable environment is discussed.     

Feeding and reproductive biology of the currito,Hoplosternum littorale,in the Venezuelan llanos with comments on the possible function of the enlarged male pectoral spines

Synopsis The reproductive biology of roach, Rutilus rutilus, was investigated during 1980–1982 in a small tributary of the eutrophic Lake rungen, southeastern Norway. The upstream migration started in early May with medium or falling water levels and water temperatures of 6–10° C, and lasted until late May or early June. Roach (both males and females) migrating early in the season were larger than roach migrating late in the season. Males matured on average one year younger than females. The first males were mature at age 2 years, the first females were mature at age 3 years. Males were smaller than females in all age groups. There was no significant year to year variation in mean length of male and female roach in the various age-groups. Mean population fecundity during 1980–1982 was estimated to be 19 × 10⁶ eggs or 63300 eggs m^–2 of spawning area. The survival rate of eggs and small roach varied considerably due to rapid and unpredictable changes in water and silt levels. Mean annual survival rates for mature male and female roach were 0.30 and 0.52, respectively. The survival rates did not vary with age.     

Life-history traits of Amur sleeper, <Emphasis Type="Italic">Perccottus glenii</Emphasis>, in the invaded Vistula River: early investment in reproduction but reduced growth rate

In recent decades, Amur sleeper is one of the most invasive fish species in Eastern and Central Europe. Generally, it is assumed that success of an invasive species can largely depend on the plasticity of its life-history traits, e.g., indicated by higher investment in reproduction in the initial stage of its invasion. On the other hand, such energy allocation to production of gonads should negatively impact somatic growth rate. The aim of this article was to explore this phenomenon in a non-native population of Amur sleeper inhabiting artificial reservoir on a large lowland river in Central Europe. Through analysis of the population age structure, sex-dependent growth rate and life-history traits we assessed investment in reproduction and its possible relationship with growth pattern as well as compared the results with literature data from native and introduced range. Samples collected monthly from April 2005 to March 2006 were used to estimate sex ratio, GSI, fecundity, eggs diameter frequency over the year, duration of spawning season, and mode of spawning. Age structure was calculated from scales and the same data were also used to back-calculate standard length (SL) at age. The population in the Włocławski Reservoir was represented by eight age groups, and its life span was one of the longest recorded both in its natural range and introduced areas. The weight–length relationship showed that the Amur sleeper grew isometrically and there was no difference between females and males. Although the Amur sleeper growth rate was relatively slow in the Włocławski Reservoir, its increment in the first year of life was comparable to that in other introduced areas and higher than in its natural range. The female age of maturation (1+) found in the reservoir was earlier than observed in its natural range as well as in most introduced areas (2+, 3+). Female length at maturation was similar to that reported elsewhere. The back-calculated standard length (SL) of females and males showed that in the first two age classes (1 and 2) males achieved larger SL than females. Meanwhile, at age 3, 4 and 5, females were larger than males but these differences were insignificant, except for class 5. For both sexes the average annual increment of SL decreased with age but in females the increment was always higher than in males (P < 0.05). The growth rate differences between females and males resulted possibly from their unequal investment in reproduction. Multiple spawning in the Włocławski Reservoir lasted from April to the end of August and was almost 3 months longer than in other regions. Thus, this higher investment in reproduction displayed by, e.g., earlier maturation of females and longer spawning season in the Włocławski Reservoir, may contribute to invasive success of Amur sleeper in newly colonized areas; however, the costs of this strategy result in slower growth in older age classes.     

The age, growth and reproduction of the stone loach Noemacheilus barbatulus (L.) in a Dorset chalk stream

SUMMARY.

• 1 In this highly productive chalk stream the stone loach, sampled by electrofishing over a 30 month period, had a high growth rate reaching a mean length of 65 mm in 1 year and 93 mm in 2 years. The fish were short-lived in contrast to most slow-growing populations in the U.K. and Finland with 11 group fish comprising 8.8% and III group fish only 1.1% of the total number.
• 2 The loach were fractional spawners: a 75 mm female produced an estimated 10,620 eggs between late April and early August totalling 46% of the loach's initial weight.
• 3 In March and April some small 0 group females contained only poorly developed eggs and up to 10% of 0 group fish may have failed to spawn.
• 4 Amongst loach >52 mm in length in March and April there was an exponential relationship between absolute fecundity and fish length but no relationship between relative fecundity and length. There was. however, a relationship between fish length and both gonadosomatic index and maximum egg size, which may indicate that large fish began to spawn first.

     

Age, growth and reproduction of the cyprinid Rutilus lemmingii (Steindachner, 1866) in the River Huebra, Central Spain

Age, growth and reproduction of the R. lemmingii population of the River Huebra, Duero basin are analysed. Females dominated older age classes and lived up to 6 years (5+) while males only reached 5 years (4+). The growing season extended from April to September; growth rates were similar for both sexes. 0+ fish condition increased during their first summer and spring. In older fish, condition cycle was related to gonad development and showed some differences between sexes. The number of females reaching maturity at age 1 + almost doubled that of males; females also matured at smaller size. Both fecundity and egg size increased with female length: mean egg counts varied between 974 for 1 + individuals and an estimated 10491 for 5+ fish. Eggs were produced as a single batch, but were released fractionally during April and May.