Autoecology of the bullhead Cottus gobio in the Province of Verbano Cusio Ossola
Codice Azione A.2. Collection of abiotic, hydromorphological and biological Titolo information necessary to plan concrete actions Codice Subazione -
Titolo - Tipo di elaborato Deliverable Stato di avanzamento Final Version Data 09.10.2018 Autori Claudio Foglini, Paolo Sala, Carolina Zellino, Pietro Volta Responsabile dell’azione CNR – Istituto per lo Studio degli Ecosistemi
Collection of abiotic, hydromorphological and biological information A B C D E F necessary to plan concrete actions
LIFE Nature and Biodiversity project LIFE15 NAT/IT/000823
Project title: Conservation and management of freshwater fauna of EU interest within the ecological corridors of Verbano-Cusio-Ossola
Project acronym: IdroLIFE
Name of the Member State: IT - Italy
Start date: 15-11-2016
End date: 14-11-2020
Coordinating beneficiary CNR - Institute of Ecosystem Study (abbrev. CNR-ISE) Associated beneficiaries Provincia del Verbano-Cusio-Ossola (PROVCO) Ente Parco Nazionale della Val Grande (PNGV) G.R.A.I.A. srl - Gestione e Ricerca Ambientale Ittica Acque (GRAIA)
Action A.2. Collection of abiotic, hydromorphological and biological information Action Title necessary to plan concrete actions Subaction - Subaction Title - Autoecology of the bullhead Cottus gobio in the Province of Verbano Cusio Title of the product Ossola. Type of product Deliverable Progress Final version Date 09.10.2018 Authors CNR – Istituto per lo Studio degli Ecosistemi Beneficiary responsible for CNR – Istituto per lo Studio degli Ecosistemi implementation Expected end date 15.06.2018
Contents
Bullhead (Cottus gobio Linnaeus, 1758) ...... 4
Distribution ...... 5
Morphological traits ...... 5
Ecology ...... 6
Reproduction ...... 7
Growth ...... 8
Status ...... 9
Cottus gobio in the study area ...... 10
Sampled habitats ...... 11
Sampling method ...... 13
Data analysis ...... 13
Results ...... 15
Discussion...... 18
References: ...... 22
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Bullhead (Cottus gobio Linnaeus, 1758)
The Cottidae (sculpins) are mostly marine fish, with around 300 species worldwide (Yokoyama & Goto, 2005). Although most sculpins live in Northern Hemisphere cool-temperate and subarctic marine habitats, some inhabits freshwater habitats. Except for the cottoids (Cottoidei) endemic to Lake Baikal, Siberia (Sideleva, 2001), the freshwater sculpins comprise the following genus: Cottus, Mesocottus, Myoxocephalus, and Trachidermus (Family Cottidae) (Goto, 1990). Among these genera, Cottus is the most specious, with about 54 species (Sideleva, 2000). The freshwater sculpins (especially Cottus and related genera), are regarded as a unique group, derived from marine sculpins, which has invaded freshwater habitats (Yokoyama & Goto, 2005). In Italy, the bullhead Cottus gobio is the only species present (Bianco, 2014), not recognizing as good species C. scaturigo and C. ferrugineus (Freyhof et al., 2005).
Fig.1 – The bullhead (Cottus gobio).
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Distribution The bullhead (Fig. 1) is widely distributed throughout Europe. It occurs from northern countries such as Greenland and Scandinavia to Italy in the south (Smyly, 1957; Mills & Mann, 1983); from northern Spain to Siberia proceeding from west to est (Witkowski, 1995). In the British Isles it is common in England and Wales, excluding northwest Wales and with only few catchments in Scotland (although Freyhof et al., 2005 ascribed British Island bullhead to Cottus perifretum species). However it is absent from Ireland (Maitland & Campbell, 1992). In Italy the specie is widespread throughout the Alps (up to 800 – 1200 m a.s.l.) and in the resurgences of the pre-alpine region. It is also present on the two mountainsides of the Tuscan- Emilian Apennines, in the Marche (in the Nera river upstream) and Umbria (Topino river, Tiber basin) regions, in the Scoltenna river (Modena province). In the Arno river it seems to be extinct (Freyhof, 2011).
Morphological traits The bullhead is a small body sized species: rarely exceeds 15 cm in length and a weight of 28 g (Maitland & Campbell, 1992). The dorso-ventral flattened tapering body, as well as the lack of a swim bladder, underline an adaptation to benthic habitat. The large head with eyes on the top makes the specie easily identifiable. The eyes have a double cornea with a fluid-filled space in-between: this may help protect the eyes from damage from moving particles or as the fish seeks shelter under stones. Other features are a strong rear-pointing spine issuing from the operculum, extremely large pectoral fins, well-developed outward-curving pelvic fins that lie flush with the bottom as the fish rests, and two dorsal fins. The first dorsal fin has six to nine spines, while the second is longer, with 15 to 18 soft rays (Bevagna et al., 1990). The mouth has an extremely wide gape, with teeth on both jaws, as well as on the front of the vomer bone. The skin have no scales, apart from 30 to 35 scale-like structures on the complete lateral line. The mottled skin, which varies in shade according to background, offers good camouflage among stones and leaf litter (Tomlison & Perrow, 2003).
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Ecology Bullhead generally prefer fast-flowing riffles habitats (Mann, 1971; Roussel & Bardonnet, 1996; Carter et al., 2004) and are frequently associated with stony substrata (gravel, cobble, pebble and boulder) rather than macrophytes (Welton et al., 1983; Copp et al., 1994; Knaepkens et al., 2002). Water depth is not considered critical: water level could ranging from 5 to 40 cm (Gosselin et al., 2010). Water speed could be also very different, ranging from 0.10 m*s-1 (Carter et al., 2004) to 1 m*s-1 (Knaepkens et al., 2002). Although mainly riverine fish species, the bullhead is also found in lakes where tributaries are present and where the water quality is suitable for their life. Bullheads are mainly nocturnal (Andreasson, 1969), and during the day they actively hiding under stones or any other available objects in order to avoid predation and in search of physical protection (Smyly, 1957). Adults are territorial, using sound as well as visual threat displays (spreading gill covers and darkening) to repel invaders. Calling is accompanied by nodding head movements during which the pectoral girdle and skull are rapidly moved against each other (Ladich, 1989). While males and females both produce sounds, males do so far more frequently, with more calling at night. A dominant individual will also approach the calls from another to chase it away. Bullheads rarely resort to fighting, and larger individuals readily oust smaller ones from their shelters. Intra-specific competition for space is present, causing spatial segregation between individuals based upon size and age (Smyly, 1957; Perrow et al., 1997). Bullheads are visual predators with large eyes, and respond to movement, although their main feeding activity takes place at dusk (and presumably dawn) and perhaps also at night (Welton et al. 1991). Benthic invertebrates comprise the bulk of the diet: crustaceans (particularly Gammarus spp. and Asellus spp.) are taken in the winter months, while a wide range of insect larvae (dipters, caddis, mayflies and stoneflies) are preferred during summer (Mills & Mann, 1983). The species also feed on other fish eggs and fry (Gandolfi et al., 1991).
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Reproduction Bullhead spawn from February to June: typically once for females in upland streams, and up to four times in warmer, more productive lowland streams (Fox 1978). Unusually among freshwater fishes, bullheads exhibit parental care within a protected environment (a “nest”). The semen biology is also unusual, intermediate between the patterns for internal and external fertilisation (Lahnsteiner et al., 1997): the structure, physiology and metabolism of the sperm are typical of an internal mechanism, but the mode of fertilisation is external (Jamieson, 1991). Males could readily distinguished at spawning time by their dark colouration, a creamy dorsal edge to the first dorsal fin, and protruding genital papillae (Tomlinson & Perrow, 2003). The fact that males are territorial and tied to their nest suggests females may exert considerable mate choice: females consistently prefer to spawn with males whose nest already contains eggs (Marconato & Bisazza, 1986), but there is also a complex pattern of female mate choice based on male body size (Bisazza & Marconato, 1988). To attract a female, the male excavates a nest under a suitable large stone, combined by the emission of acoustic 'knocking' sounds. These acoustical emissions may have also a territorial function (Ladich, 1989). Within 20-30 hours of entering the nest, the female spawns a clump of up to 400 sticky eggs (1.5- 2.5 mm diameter), which adhere to the ceiling of the stone (Mills & Mann, 1983; Gandolfi et al., 1991). Because some males may attract more than one female (usually from 4 to 10), several batches of eggs at different stages of development and laid successively may be found in the nest of a single male bullhead (Smyly, 1957). After the departure of the females, the male remains in the nest until the eggs hatch (Mills & Mann, 1983). During incubation the male defends the brood against egg predators and manages the nest by fanning the eggs with his pectoral fins (Morris, 1954). It is thought the male fasts at this time, although he may consume some eggs to survive, especially if stressed (Tomlinson & Perrow, 2003). In case of reduced foraging possibility during parental care, parental-type cannibalism phenomena were observed (Marconato & Bisazza, 1988). The eggs hatch after 20 to 30 days, depending on water temperature. The incubation period at 10°C takes about four weeks (Mills & Mann, 1983). The newly hatched larvae (6–7 mm in length) are supplied by a large yolk sac, which is absorbed in about 10 days, after which fries are ready to disperse (Maitland & Campbell, 1992).
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Growth Generally, bullheads attain a length of 40–50 mm after their first year, 60 mm after their second and 70–90 mm after their third (Maitland & Campbell, 1992) but the growth rate, the age of sexual maturity and the longevity of bullheads vary greatly in different habitats. In hard-water streams and lakes (rich in CaCO3 and usually alkaline) growth is faster, while is slower in soft (acid) water where the calcium concentration is low. Trends in longevity are in the opposite direction however, with the oldest fish surviving only three or, in one case, four years in the hard waters and from four up to ten years in soft waters (Mills & Mann, 1983). Also in Italian freshwater two different trends in growth and life cycle could be marked. In the water resurgences of pre-Alpine region growth is fast but the life cycle is short, with a maximum length of 12.5 cm and maximum age of 4-5 years. Mountain habitats were marked by a longer life cycle and slower growth (9-10 years, with length of 15-16 cm) (Zerunian, 2002). Sexual maturity is reached between the first and the second year into resurgences, and between the second and the fourth year into mountain river (Zerunian, 2002). Parameters of some length-weight relationship (Weight = a*lengthb) for the bullhead known in literature are listed in Table 1.
Tab.1 – Bullhead length-weight relationship parameters available in the literature. References a b Country Mann, 1971 0.012 3.155 UK Mann, 1971 0.014 3.051 UK Mann, 1971 0.012 3.133 UK Mann, 1971 0.012 3.134 UK Mann, 1971 0.011 3.121 UK Treer et al., 2008 0.0097 3.128 Croatia Froese & Pauly, 2016 0.007 3.304 Italy Lorenzoni et al., 2018 0.030 2.635 Italy Lorenzoni et al., 2018 0.023 2.719 Italy Lorenzoni et al., 2018 0.025 2.689 Italy Lorenzoni et al., 2018 0.008 3.230 Italy Lorenzoni et al., 2018 0.010 3.162 Italy
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Status Except sporadic human consumption in the past (Maitland & Campbell 1992), the species nowadays have no economic value, so it was therefore rarely managed by humans (Mann, 1971), except as a live bait for larger fish species (Tomlinson & Perrow, 2003). Bullhead occurrence is considered to be a useful indicator of the health, integrity and naturalness of running waters (Tomlinson & Perrow, 2003), but in several countries of continental Europe the bullhead is endangered as a result of habitat degradation (Knaepkens et al., 2004a, b). The principal threats to the species are the following: - Deposition of fine sediments over hard and coarse substrates reduces the available habitat necessary for bullhead reproduction and shelter. Sediments deposition could be triggered by any work likely to affect flow dynamics (weirs, dams, barrages) and by the agricultural intensification. - The creation, in the riverbed, of vertical structure higher than 18-20 cm (considered impassable to bullhead according to Utzinger et al., 1998) could lead to population fragmentation and isolation (Fisher & Kummer, 2000). - The removal or modification of natural features of the riverbed (such as channelization, straightening, widening, deepening, and isolation of the channel), and any alteration of the natural flow regimes, could be detrimental to bullhead populations (Tomlinson & Perrow, 2003). Dredging operations reduce the hard substrate available to bullhead, increasing at the same time the exposure to predators (Perrow et al., 1997). - The massive release of brown trout and rainbow trout for fishing purposes could greatly increase the predation pressure over bullhead populations, especially if a large numbers of large fish is released (Lorenzoni et al., 2018). Also alien crayfish such as Astacus leptodactylus and Procambarus clarkii have been proven to have a detrimental effect on bullhead populations through competition for shelter and food, and also by direct predation (Guan & Wiles 1997). For all these reasons bullhead is listed under the Annex II of the Council Directive 92/43/EEC (European Commission, 1992). In Italy, the bullhead is listed in the general action plan for Italian freshwater fish conservation (Zerunian, 2003) and classified as “Least concern species” in the Italian Vertebrates Red List (Rondinini et al., 2013).
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Cottus gobio in the study area According to the literature available for the VCO Province (Regione Piemonte, 1991; G.R.A.I.A. s.r.l.,1995; 1999) and to the sampling campaign included in the project IdroLIFE, the bullhead is present in the river Toce (upper and middle course), Bogna, Anza (upper course) and Strona. It is also present in the streams Ovesca, Ermo, Fiumetta, San Bernardino and San Giovanni. The actual distribution of the species is summarized in Fig. 2.
6, 7
4, 5 3
2 8
9
1
Fig. 2 – Occurrence of bullhead in the VCO province; stations sampled during IdroLIFE project are labelled with numbers (see Tab.2).
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Sampled habitats Investigated habitat typology varies from braided channels (Fig.3a) and (Fig.3b) of river foothill, to mountain stream of medium (Fig.3c) and low altitude (Fig.3d).
a) Lake Tana downstream (295 m). b) Lake Tana upstream (300 m).
c) Orfalecchio (600 m). d) Ramello (290 m). Fig. 3 – Pictures of the different habitats sampled. Mean altitude (meters a.s.l.) is showed in brackets.
During the IdroLIFE project, the bullhead was sampled in 9 of the 29 sites explored. Below is given a brief description of the sites with bullhead presence. The following seven sampling station are located along the Toce river. Gravellona Toce (Label 1) is located into the main flow of a typical foothill river, with large riverbed, fast flow and deep water. The bottom is mainly composed by sand and silt, with strong presence of macrophytes, and riverine vegetation roots along the banks. Prata (Label 2) is located immediately downstream of the Prata dam, in the medium course of the River Toce. The river shows a wide riverbed and deep, slow-flowing water. The bottom is mainly sandy, with pebbles and scattered stones. Rocks are also present in some traits along the banks.
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Six Arches bridge (Label 3) is a mild-flow run environment, with riffle-pool series near the bridge. Riverbed is wide, mainly pebbly with scattered small rocks. In the upstream parts, the river branches into secondary channels with slow-running water with riverine vegetation along both banks. Mizzoccola bridge (Label 4 – downstream; Label 5 – upstream) sites are located in the main Toce course. Riverbed is wide, mainly composed by blocks downstream, and pebbles with scattered macrophytes cover upstream. Rocks are present along some traits of both banks and near the bridge pylons. Water is fast-flowing and shallow into the downstream riffles, but deeper in the upstream part and in pools. Lake Tana sites are located straddling the namesake dam. The downstream site (Label 6) is characterised by a funnelled stony riverbed with fast-flowing water, very deep near the dam and shallow in the riffles. The upstream station (Label 7) shows wide, pebbly riverbed rich in riverine vegetation and with scattered macrophytes cover. Water has intermediate deep and moderate flow. The other two sampled station are located into different habitat type. Valgrande is a typical medium-altitude stream, with narrow and steep riverbed. In Orfalecchio (Label 8) water is fast- flowing, and the bottom is composed mainly by scattered boulders and stones without macrophytes. Water is mainly shallow, but there are many small falls and pools with deep water. Ramello (Label 9) is located into the San Giovanni, a low-altitude mountain stream. Riverbed is quite large and uniform, mainly composed by medium-size blocks and scattered pebbles. Water is shallow and fast-flowing in riffles, but moderately deep in some pools. Environmental data concerning sampled sites are summarised in Table 2.
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Tab. 2 – Summary of sampled stations features. In the sampling station column D and U are used as “downstream” and “upstream” respectively.
Map Altitude Max depth Riverbed Flow River Sampling station Bottom label (m a.s.l.) (m) width (m) speed 1 Gravellona Toce 200 4.5 190 Fast Sand/silt 2 Prata D 228 2.5 27 Slow Sand/pebbles
3 Six Arches bridge 240 1.8 50 Mild Pebbles/rocks 4 Mizzoccola bridge D 258 1.6 65 Fast Rocks 5 Mizzoccola bridge U 265 2 45 Mild Pebbles
Toce River 6 Lake Tana D 295 2 50 Fast Rocks 7 Lake Tana U 300 2.5 33 Mild Pebbles
8 Orfalecchio 600 2.5 20 Fast Rocks/boulders
Rio
Stream
Valgrande
9 Ramello 290 1.5 30 Fast Pebbles/rocks
San
Stream
Giovanni
Sampling method Fish were sampled by electrofishing along transects, using a back-packed built-in frame ELT60II- GI (Hans Grassl GmbH, 1.3 kW, 300/500V, DC and pulse current output) set up with a copper cathode (width 2.5 cm, length 300 cm) and steel ring anode (thickness 0.8 cm, diameter 50 cm) and used only in DC mode. Stunned fish were scooped out with a fine-mesh dip-net, measured (total length, ± 0.1 cm) and weighted (± 1 g) (Murphy & Willis, 1996). After sampling, fish were placed in holding boxes to recover and then released.
Data analysis In order to provide a picture about the bullhead status in the area of interest, the following parameters were calculated. Mean length, mean weight, linear abundance and linear mass density: the number of individuals or the grams of fish per meter of river, and the average length and weight of fish in different streams, allow us to compare effectively the different areas sampled, highlighting at the same time any
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differences between populations. This gives a summary information on the effects of different environmental factors on them.
Length-frequency distribution: it reflects an interaction of rates of reproduction, recruitment, growth and mortality of the age-groups present in the sampled population. The distribution itself, or distribution changes over time, could help in understanding population dynamics such as low recruitment, slow growth or excessive mortality (Murphy & Willis, 1996).
Growth: it is illustrated through the analysis of the length-weight relationship. We can’t use length- age relationship because, due to the lacking of scales in bullhead skin, was not possible conduct scalimetric analysis. Length-weight relationship is calculated through the equation Weight = a * length b . The "b" coefficient usually is included between 2.6 and 3.4, and represents a synthetic indicator of the corpulence of the individuals making up the population, and indirectly indicates their health state (Froese, 2006). The higher the coefficient, the more the fish is corpulent, and therefore "fat". On the contrary, a low coefficient indicates "thin" fish. A standard, or good growth, is assessed when the coefficient falls within the above-mentioned limit (2.6-3.4).
Estimation of asymptotic length and length at first maturity: Maximum length (Lmax) reached by fishes is an important parameter that is highly correlated with metabolism and most other life history traits. However, obtaining maximum length estimates for commercial fishes has become difficult due to the extirpation of large specimens by intensive fishing (Binohlan & Froese, 2009). Conversely, obtain length at first maturity (Lm; namely the length where on the average 50% of the fish in a population reach sexual maturity) is almost impossible without killing specimens to inspect their gonads: this is highly not recommended for species of conservation interest. Lm is an important management parameter used to monitor whether enough juveniles in an exploited stock mature and spawn. Another important parameter is the asymptotic length (Linf), namely the mean length the fish of that population would reach if they would continue to grow indefinitely (Froese & Binohlan, 2000). Through empirical equations is possible to derive Linf and Lm from the maximum length of fish, and vice versa (Froese & Binohlan, 2000).
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Results A total of 154 bullhead were sampled in nine sites. The species is present into seven station of the Toce river (label 1, 2, 3, 4, 5, 6, 7), and into one of both the Rio Valgrande (label 8) and the San Giovanni (label 9) streams. Morphometric characteristics of the sampled fish are summarized in Table 3. Table 4 reports fish linear density in each site (number of individuals and biomass*meters-1), along with trout density (sum of marble, brown, rainbow trouts) for further comparison. For each bullhead population we also calculated the length-frequency distribution of individuals (Fig. 4) and the length-weight relationship (expressed as: weight = a*lengthb) with associated parameters (Tab. 5).
Tab. 3 – Summary of bullhead sampled during the IdroLIFE Project. In the sampling station column D and U are used as “downstream” and “upstream” respectively.
Map Length (cm) Range (cm) Weight (g) Range (g) River Sampling station n label Mean (± S.E.) Min – Max Mean (± S.E.) Min – Max 1 Gravellona Toce 12.50 ± 0.26 12.0 – 12.9 22.00 ± 1.00 21.00 – 24.00 3 2 Prata D 13.0 ± 1.0 12.0 – 14.0 28.91 ± 6.18 22.74 – 35.09 2
3 Six Arches bridge 9.50 ± 0.49 6.2 – 12.0 13.70 ± 1.75 2.00 – 22.00 14 4 Mizzoccola bridge D 11.20 ± 0.44 9.0 – 14.6 19.46 ± 1.79 10.00 – 32.00 13 5 Mizzoccola bridge U 8.12 ± 0.12 8.0 – 9.3 07.61 ± 0.35 7.26 – 11.09 11
Toce River 6 Lake Tana D 10.06 ± 1.31 8.0 – 14.3 16.39 ± 5.63 7.65 – 35.00 5 7 Lake Tana U 10.29 ± 0.28 6.0 – 12.7 15.47 ± 1.02 3.23 – 26.67 28
8 Orfalecchio 7.32 ± 0.72 3.0 – 12.0 6.79 ± 1.38 1.0 – 17.0 15
Rio
Stream
Valgrande
9 Ramello 9.68 ± 0.19 4.6 – 12.5 11.87 ± 0.69 2.00 – 26.00 63
San
Stream
Giovanni
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Tab. 4 – Bullhead and trout densities. Bullhead densities Trout densities Map River Sampling station label Fish*m-1 g*m-1 Fish*m-1 g*m-1
1 Gravellona Toce 0.001 0.026 0.002 0.136 2 Prata D 0.029 0.826 0.143 66.838
3 Six Arches bridge 0.030 0.426 0.189 10.736 4 Mizzoccola bridge D 0.043 0.844 0.243 22.460 5 Mizzoccola bridge U 0.056 0.431 0.380 24.564
Toce River 6 Lake Tana D 0.056 0.910 0.210 33.956 7 Lake Tana U 0.165 2.547 0.159 5.024
8 Orfalecchio 0.017 0.113 0.128 10.918
Rio
Stream
Valgrande
9 Ramello 0.210 2.493 n.d. n.d.
San
Stream
Giovanni
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c) Toce river
b) San Giovanni stream
a) Valgrande stream
Fig. 4 - Length-frequency distribution into the three sampled streams.
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Tab. 5 – length-weight relationship and related parameters. Stream Length range (cm) Weight range (cm) a b Toce River 6.0 – 14.6 2.0 - 35.1 0.0208 2.8159 San Giovanni stream 4.6 – 12.5 2.0 - 26.0 0.0225 2.7248 Rio Valgrande stream 3.0 – 12.0 1.0 - 17.0 0.0977 2.0459
Discussion Sites sampled during the project were grouped by river, in order to characterize the different bullhead populations hosted in each stream. According to one-way ANOVA analysis (SPSS 13.0), there are significant differences in length
(F2,151 = 14.19, P < 0.05) and weight (F2,151 = 12.91, P < 0.05) between the three populations. Using Tuckey post-hoc tests, the following differences among bullhead populations emerge. Concerning mean length, fishes in the Toce river are longer than fishes in Valgrande stream (P < 0.05), but similar to those in San Giovanni stream (P = 0.33). Fishes in San Giovanni are longer than those in Valgrande (P < 0.05). Details are shown in Table 6.
Tab. 6 – Tuckey post-hoc test details about bullhead mean length. 95 % Confidence Interval Contrast S. E. Sig. Lower bound Upper bound
Toce vs San Giovanni 0.32 0.33 -0.30 1.21
h Toce vs Valgrande 0.53 0.00 1.57 4.07
Lengt San Giovanni vs Valgrande 0.53 0.00 1.09 3.64
About the mean weight (Tab. 7), bullhead in the Toce river are heavier than fishes in San Giovanni (P < 0.05), which are in turn heavier than specimens in Valgrande (P < 0.05).
Tab. 7 – Tuckey post-hoc test details about bullhead mean weight. 95 % Confidence Interval Contrast S. E. Sig. Lower bound Upper bound
Toce vs San Giovanni 1.10 0.01 0.87 6.07 ht Toce vs Valgrande 1.82 0.00 4.24 12.87
Weig San Giovanni vs Valgrande 1.85 0.02 0.70 9.48
Comparing length-frequency distributions, Toce River (Fig.4a) and San Giovanni stream (Fig.4b) showed an high number of specimens longer than 75 mm. This size is usually associated to big
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males (more likely to attract females and defend their eggs) or/and large female (potentially making a high contribution to population fecundity): both are good signs of an healthy population (Tomlinson & Perrow, 2003). The presence of heavier fishes in the Toce River (see Tab.7) could be related to a more productive environment, associated with great food abundance. Valgrande stream population (Fig.4c) is characterized by smaller fishes (see Tab.6 and 7) and the preponderance of juvenile specimens (age 1 and/or 1+, see Growth paragraph), with a progressive reduction in the number of individuals at the increasing in size.
The “b” parameter of the length-weight relationship plotted for each stream (Tab. 5) is similar to those listed in Lorenzoni et al., 2018 (Tab. 1 for comparison). Only bullhead population in the Valgrande stream show a non-optimal corpulence indicator (2.05), lower than the optimal range (2.6-3.4).
According to Froese & Binohlan (1999), if the maximum size reached in a population is known, the estimation of the asymptotic length (Linf) is possible. From Linf, also the length at first maturity (Lm) could be inferred. These parameters are summarised in Table 8.
Tab. 8 – Linf & Lm Stream Linf (95% C.I.) Lm (95% C.I.) Toce River 15.5 (15.2-15.8) 9.8 (8.7-11) San Giovanni stream 13.3 (13-13.5) 8.5 (7.5-9.7) Rio Valgrande stream 12.8 (12.5-13) 8.2 (7.2-9.4)
Bullhead population of the Valgrande stream show an overall small size, a low asymptotic length and an early maturity. These elements could be related to a less productive environment and/or a high predatory pressure (Marconato, 1986). Valgrande stream is characterised by a great presence of brown trout, which in many traits of the stream monopolizes the fishing community. In the Toce River, linear abundance of bullhead and trout (marble, brown and rainbow) follow a similar trend: they directly increase with altitude (Fig. 5). In Italy bullhead is often syntopic with brown trout: both species are reported to have similar ecological preferences and similar feeding habits, however are reported some diversifications in their diet and microhabitat preferences (Lorenzoni et al., 2018).
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Fig. 5 – Bullhead (dot) and trout (square) linear abundance related to altitude in the Toce River.
Table 9 compares the trout vs bullhead abundance ratio in the Toce River and the Valgrande stream. We point out that, if the median value of the linear abundance ratio in the Toce River is not so low than the value recorded into the Rio Valgrande, the situation for the biomass linear density is very different. In this case, the value calculated for the Valgrande stream is more than 3.5 x the median value in the Toce River.
Tab. 9 – Trout vs bullhead density ratio (median value) Stream Fish*m-1 g*m-1 Gravellona Toce 2.40 3.63 Prata D 4.93 80.92 Six Arches bridge 6.30 36.29 Mizzoccola bridge D 5.65 38.32 Mizzoccola bridge U 6.79 82.07 Lake Tana D 3.75 53.73 Lake Tana U 0.96 1.97 Toce River (median value) 4.93 38.32 Rio Valgrande stream 7.53 139.13
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Although fish data concerning each investigated section are not directly comparable (non-standard transect, different species susceptibility to electrofishing), collected elements lead to the following considerations. Although into the Valgrande stream trout’s linear abundance is not much higher than in the Toce River, the most marked difference is in biomass fish density. It is therefore clear that in the Valgrande stream, for each bullhead sampled, trouts are much heavier than in the Toce River. It is therefore conceivable to indicate that the reduced presence of bullhead in Valgrande is attributable, as well as to a poorer environment, especially to the strong presence of medium-large trouts, able to exert a considerable predatory pressure on the species (Lorenzoni et al., 2018). This could be probably due to the fishery management policy implemented in the area: opposite to the Toce River where fishing is allowed, angling into the Valgrande stream has been closed for many years and is currently only permitted as catch-and-release. Another interesting point about Valgrande bullhead population, is its strongly localized distribution. We found specimens only in 1 of the 11 sites this area, although sample points environmental characteristics were substantially similar. Water varies from shallow to mildly deep, with fast flowing water. Riverbed is generally narrow, composed by rocks and boulders without macrophytes cover. Shading varies within each stream but is generally moderate, thanks to wood presence on the surroundings slopes. Apparently, the only obstacle that may impede bullhead presence could be the torrential aspect of most of the explored rivers, which during the year can incur great variations in the water flow. Another obstacle is the presence of small man-made bridles (Fig. 6) and occasional waterfalls (Fig.7). If their height is more than 20 cm, they are an impassable barrier for the species (Utzinger et al., 1998).
Fig. 6 – Bridle in the Rio Prata stream Fig. 7 – Waterfall and bridle in the Rio Crot stream
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References:
Andreasson S. (1969). Locomotory activity patterns of Cottus poecilopus Heckel and C. gobio L. (Pisces). Oikos 20, 78-94.
Bevagna D., Giovinazzo G., Lorenzoni M., Mearelli M., Petesse M. (1990). Segnalazioni di Cottus gobio (Osteichthyes, Cottidae) in alcuni corsi d’acqua umbri. Riv. Idrobiol. 29, 113 - 122.
Bianco P.G. (2014). An update on the status of native and exotic freshwater fishes of Italy. J. Appl. Ichthyol. 30, 62-77.
Bisazza A. & Marconato A. (1988). Female mate choice, male-male competition and parental care in the river bullhead, Cottus gobio L. (Pisces, Cottidae). Anim. behav. 36, 1352-1360.
Carter M.G., Copp G.H. & Szomlai V. (2004). Seasonal abundance and microhabitat use of bullhead Cottus gobio and accompanying fish species in the River Avon (Hampshire), and implications for conservation. Aquat. Conserv. 14, 395-412.
Copp G.H., Warrington S. & de Bruine Q. (1994). Comparison of diet in bullhead, Cottus gobio and stone loach, Barbatula barbatula in a small English lowland river. Folia Zool. 43, 171—176.
Englbrecht C.C., Freyhof J., Nolte A., Rassmann K., Schliewen U. & Tautz D. (2000). Phylogeography of the bullhead Cottus gobio (Pisces: Teleostei: Cottidae) suggests a pre- Pleistocene origin of the major central European populations. Mol. Ecol. 9, 709–722.
European Commission (1992). Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora. Off. J. European Union 35, 7-50.
Fisher S., & Kummer H. (2000). Effects of residual flow and habitat fragmentation on distribution and movement of bullhead (Cottus gobio L.) in an alpine stream. Hydrobiologia 422/423, 305-317.
Freyhof J. (2011). Cottus gobio (errata version published in 2016). The IUCN Red List of Threatened Species 2011: e.T5445A97802083. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T5445A11147263.en. Downloaded on 22 June 2018.
Freyhof J., Kottelat M., Nolte A. (2005). Taxonomic diversity of European Cottus with description of eight new species (Teleostei: Cottidae). Ichthyol. Explor. Freshwat 16, 107-172.
Froese R. (2006). Cube law, condition factor and weight–length relationships: history, meta- analysis and recommendations. J. Appl. Ichthyol. 22, 241–253.
Froese R. & Binohlan C. (2000). Empirical relationships to estimate asymptotic length, length at first maturity and length at maximum yield per recruit in fishes, with a simple method to evaluate length frequency data. J. Fish Biol. 56, 758–773.
LIFE15 NAT/IT/000823 - Action A.2. Collection of abiotic, Page 22 of 25 hydromorphological and biological information necessary to plan concrete actions”
Froese R. & Pauly D. (Eds) (2016). FishBase. World Wide Web electronic publication. http://www.fishbase.org , version (01/2016).
Fox P.J. (1978). Preliminary observations on different reproductive strategies in the bullhead (Cottus gobio L.) in northern and southern England. J. Fish Biol. 12, 5–11.
Gandolfi G., Zerunian S., Torricelli P., Marconato A. (1991). I pesci delle acque interne italiane. Istituto Poligrafico e Zecca dello Stato, Roma.
Gosselin M.-P., Petts G.E., Maddock I.P. (2010). Mesohabitat use by bullhead (Cottus gobio). Hydrobiologia 652, 299–310.
Goto A. (1990). Alternative life-history styles of Japanese freshwater sculpins revisited. Env. Biol. Fish. 28, 101–112.
G.R.A.I.A. s.r.l. (1995). Studio ecologico per la gestione ittica del Parco Naturale Alpe Veglia e Alpe Devero. Unpublished data.
G.R.A.I.A. s.r.l. (1999). Piano Ittico del VCO: dati raccolti - fauna ittica, qualità delle acque e habitat fluviale. Unpublished data.
Guan R.-Z. & Wiles P.R. (1997). Ecological impact of introduced crayfish on benthic fishes in a British lowland river. Conserv. Biol. 11, 641-647.
Jamieson B.G.M. (1991). Fish Evolution and Systematics: Evidence from Spermatozoa. Cambridge, Cambridge University Press.
Knaepkens G., Bruyndoncx L., Bervoets L. & Eens M. (2002). The presence of artificial stones predicts the occurrence of the European bullhead (Cottus gobio) in a regulated lowland river in Flanders (Belgium). Ecol. Freshwat. Fish 11, 203–206.
Knaepkens G., Bruyndoncx L., Coeck J. & Eens M. (2004a). Spawning habitat enhancement in the European bullhead (Cottus gobio), an endangered freshwater fish in degraded lowland rivers. Biodivers. Conserv. 13, 2443–2452.
Knaepkens G., Bruyndoncx L. & Eens M. (2004b). Assessment of residency and movement of the endangered bullhead (Cottus gobio) in two Flemish rivers. Ecol. Freshwat. Fish 13, 317–322.
Ladich F. (1989). Sound production by the river bullhead, Cottus gobio L. (Cottidae,Telostei). J. Fish Biol. 35, 531–538.
Lahnsteiner F., Berger B., Weismann T. & Patzner R.A. (1997). Sperm structure and motility of the freshwater teleost Cottus gobio. J. Fish Biol. 50, 564–574.
LIFE15 NAT/IT/000823 - Action A.2. Collection of abiotic, Page 23 of 25 hydromorphological and biological information necessary to plan concrete actions”
Lorenzoni M., Carosi A., Giovannotti M., Porta G.L., Splendiani A., Barucchi V.C. (2018). Population status of the native Cottus gobio after removal of the alien Salmo trutta: a case-study in two Mediterranean streams (Italy). Knowl. Manag. Aquat. Ecosyst. 419, 22.
Maitland P.S. & Campbell R.N. (1992). Freshwater Fishes of the British Isles. Harper Collins, London.
Mann R.H.K. (1971).The populations, growth and production of fish in four small streams in Southern England. J Anim. Ecol. 40, 155–190.
Marconato A. (1986). Distribuzione dell'ittiofauna e gestione della pesca. Quaderni ETP 14: 139– 149.
Marconato A. & Bisazza A. (1986). Males whose nests contain eggs are preferred by female Cottus gobio L. (Pisces, Cottidae). Anim. Behav., 34, 1580-1582.
Marconato A. & Bisazza A. (1988). Mate choise, egg cannibalism and reproductive success in the river bullhead, Cottus gobio L. J. Fish Biol. 33, 905-916.
Mills C.A. & Mann R.H.K. (1983). The bullhead Cottus gobio, a versatile and successful fish. Annual Reports of the Freshwater Biological Association 51, 76–88.
Morris D. (1954). The reproductive behaviour of the river bullhead (Cottus gobio), with special reference to the fanning activity. Behaviour 7, 1-32.
Murphy B.R. & Willis D.W. (1996). Fisheries techniques. Second Edition. American Fisheries Society. Bethesda, Maryland.
Perrow M.R., Punchard N.T. & Jowitt A.J.D. (1997). The habitat requirements of bullhead (Cottus gobio), and brown trout (Salmo trutta) in the headwaters of selected Norfolk rivers: implications for conservation and fisheries. Report to the Environment Agency, Eastern Area, Anglian Region, Ipswich.
Regione Piemonte (1991). Carta ittica relativa al rerritorio della Regione Piemontese. Assessorato Caccia e Pesca. Torino (II vol).
Rondinini C., Battistoni A., Peronace V., Teofili C. (2013). Lista Rossa IUCN dei Vertebrati Italiani. Comitato Italiano IUCN e Ministero dell’Ambiente e della Tutela del Territorio e del Mare, Roma.
Roussel J.M. & Bardonnet A. (1996). Differences in habitat use by day and night for brown trout (Salmo trutta) and sculpin (Cottus gobio) in a natural brook: multivariate and multi-scale analyses. Cybium 20, 45–53.
Sideleva V.G. (2000). A New Sculpin Species Cottus sabaudicus sp. nova (Scorpaeniformes: Cottidae) from the Savoy District, France. J. Ichthyol. 49, 209-214.
LIFE15 NAT/IT/000823 - Action A.2. Collection of abiotic, Page 24 of 25 hydromorphological and biological information necessary to plan concrete actions”
Sideleva V.G. (2001). List of fishes from Lake Baikal with descriptions of new taxa of cottoid fishes. In: Pugachev O.N., Balushkin A.V. (Eds.), New Contributions to Freshwater Fish Research. Proceedings of Zoological Institute Ras. St. Petersburg.
Smyly W.J.P. (1957). The life history of the bullhead or Miller's thumb (Cottus gobio L.). Proc. Zool. Soc. Lond. 128, 431–453.
Tomlinson M.L. & Perrow M.R. (2003). Ecology of the Bullhead. Conserving Natura 2000 Rivers Ecology Series No. 4. English Nature, Peterborough.
Treer T., Šprem N., Torcu-Koc H., Sun Y., Piria M. (2008). Length–weight relationships of freshwater fishes of Croatia. J. Appl. Ichthyol. 24, 626-628.
Utzinger J., Roth C. & Peter A. (1998). Effects of environmental parameters on the distribution of bullhead Cottus gobio with particular consideration of the effects of obstructions. J. Appl. Ichthyol. 35, 882–892.
Welton J.S., Mills C.A. & Pygott J.R. (1991).The effect of interaction between stone loach Noemacheilus barbatulus (L.) and the bullhead Cottus gobio (L.) on prey and habitat selection. Hydrobiologia 220, 1–7.
Welton J.S., Mills C.A. & Rendle E.L. (1983). Food and habitat partitioning in two small benthic fishes, Noemacheilus barbatulus (L .) and Cottus gobio L . Arch. Hydrobiol. 97, 434-454.
Witkowski A. (1995). Phenotypic variability of Cottus gobio Linnaeus, 1758 in Polish waters (Teleostei: Scorpaeniformes: Cottidae). Zool. Abh. Staatl. Mus. Tierkd. Dresden 48, 177–183.
Yokoyama R. & Goto A. (2005). Evolutionary history of freshwater sculpins, genus Cottus (Teleostei; Cottidae) and related taxa, as inferred from mitochondrial DNA phylogeny. Mol. Phylogenetics Evol. 36, 654–668.
Zerunian S. (2002). Pesci delle acque interne italiane. Quaderni di conservazione della natura 20, 122 -127.
Zerunian S. (2003). Piano d'azione generale per la conservazione dei pesci d'acqua dolce in Italia. Quaderni di conservazione della natura 17, 1-129.
LIFE15 NAT/IT/000823 - Action A.2. Collection of abiotic, Page 25 of 25 hydromorphological and biological information necessary to plan concrete actions”