Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help
Researched by | Karen Riley | Refereed by | Prof. Robert Patzner |
Authority | Miller & El-Tawil, 1974 | ||
Other common names | - | Synonyms | - |
Gobius couchi is a typically shaped goby, reaching a maximum of 9 cm in length. It is fawn brown to grey in colour with dark markings on its back. There is a deeper-than-long dusky patch at the upper base of the pectoral fin and five dark lateral blotches. It is also found with one, or sometimes two dark spots on the cheeks. There are 35-45 rows of scales along the sides, from the pectoral fin to the tail fin.
Couch's goby is a very localised, rare and protected species. It is found low shore under red or green algae in south Cornwall and north west Ireland, below high tide level in County Cork and sublittorally in a sheltered sea lough in south Ireland.
Phylum | Chordata | Sea squirts, fish, reptiles, birds and mammals |
Class | Actinopterygii | Ray-finned fish, e.g. sturgeon, eels, fin fish, gobies, blennies, and seahorses |
Order | Gobiiformes | |
Family | Gobiidae | |
Genus | Gobius | |
Authority | Miller & El-Tawil, 1974 | |
Recent Synonyms |
Typical abundance | Low density | ||
Male size range | up to 9cm | ||
Male size at maturity | |||
Female size range | Small-medium(3-10cm) | ||
Female size at maturity | |||
Growth form | Pisciform | ||
Growth rate | |||
Body flexibility | High (greater than 45 degrees) | ||
Mobility | |||
Characteristic feeding method | |||
Diet/food source | |||
Typically feeds on | Algae, crustaceans, bivalves and polychaetes. | ||
Sociability | |||
Environmental position | Demersal | ||
Dependency | Independent. | ||
Supports | None | ||
Is the species harmful? | No |
Gobius couchi is a rare British marine fish which feeds on algae, crustaceans, bivalves and polychaetes. It is known to reach a maximum of 9 cm in length and has a lifespan of approximately 6 years.
Physiographic preferences | Open coast, Enclosed coast / Embayment |
Biological zone preferences | Sublittoral fringe |
Substratum / habitat preferences | Fine clean sand, Maerl, Mixed, Mud, Muddy sand, Pebbles, Rockpools, Sandy mud, Under boulders |
Tidal strength preferences | |
Wave exposure preferences | Sheltered |
Salinity preferences | See additional Information |
Depth range | 0.5 to 16 m |
Other preferences | |
Migration Pattern | Non-migratory / resident |
Reproductive type | Gonochoristic (dioecious) | |
Reproductive frequency | Annual protracted | |
Fecundity (number of eggs) | See additional information | |
Generation time | Insufficient information | |
Age at maturity | Insufficient information | |
Season | Spring - Summer | |
Life span | See additional information |
Larval/propagule type | - |
Larval/juvenile development | Oviparous |
Duration of larval stage | No information |
Larval dispersal potential | 1 km -10 km |
Larval settlement period | Insufficient information |
The MarLIN sensitivity assessment approach used below has been superseded by the MarESA (Marine Evidence-based Sensitivity Assessment) approach (see menu). The MarLIN approach was used for assessments from 1999-2010. The MarESA approach reflects the recent conservation imperatives and terminology and is used for sensitivity assessments from 2014 onwards.
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
Intermediate | High | Low | Moderate | |
Gobius couchi lives and forages on a variety of substrata. It requires rockpools in the intertidal to survive at low tide. Therefore, loss of rockpools (for instance, by infilling) or rocky substrata (for instance, by spoil dumping or land claim) will most likely cause a proportion of the species population to die. However, at high tide adults are sufficiently mobile and will be able to recolonize areas which contain suitable substrata. Intolerance to substratum loss is assessed as intermediate. Recoverability is likely to be high (see Additional Information section below). | ||||
Intermediate | High | Low | Moderate | |
Gobius couchi will not be affected by smothering as they are mobile and able to swim away. However, destruction of habitat is important. Cordone & Kelley (1961) reported that (in a freshwater habitat) deposition of sediment on the bottom of the substratum would destroy needed shelter, reduce the availability of food, impair growth and lower the survival rate of eggs and larvae of fish. It is likely that Gobius couchi would be more intolerant if smothering occurred during the breeding season due to the probable destruction of broods of eggs. Materials such as concrete, oil or tar are likely to have a greater negative impact on the population. Intolerance due to smothering is assessed as intermediate. Recoverability is likely to be high (see Additional Information section below). | ||||
Low | High | Low | Low | |
Moore (1977) indicated that an increase in siltation can have a negative effect on the growth of adult fish, survival of eggs and larvae and pathological effects on gill epithelia. Bottom-dwelling species are generally found to be tolerant of suspended solids (Moore, 1977). Juveniles have been reported as being more intolerant of siltation than adults (Moore, 1977). Therefore, intolerance has been recorded as low. Recoverability is likely to be high (see Additional Information section below). | ||||
Tolerant | Not relevant | Not sensitive | Moderate | |
Gobius couchi is likely to be tolerant of a decrease in suspended sediment. | ||||
High | Moderate | Moderate | Moderate | |
Gobius couchi is found intertidally, in shallow rock pools. It can shelter in rock crevices and under boulders or weed, where the risk of desiccation is minimized. The animal is soft-bodied, so stranding of the individual, and subsequent exposure to sunshine and air for an hour would more than likely result in a proportion of the population dying. Intolerance to desiccation is therefore recorded as high. Recoverability is likely to be moderate (see Additional Information section below). | ||||
Tolerant | Not relevant | Not sensitive | Low | |
It is unlikely that Gobius couchi would be affected by a change in the emergence regime as at high tide it forages near the shore and at low tide it inhabits rock pools. | ||||
Tolerant | Not relevant | Not sensitive | Low | |
It is unlikely that Gobius couchi would be affected by a change in the emergence regime as at high tide it forages near the shore and at low tide it inhabits rock pools. | ||||
Low | Very high | Very Low | Low | |
The ability of Gobius couchi to shelter in crevices between large boulders would be able to shield them from a moderate increase in the water flow rate. However, it is unlikely that they could withstand a large increase in water flow rate, as this would decrease the goby's ability to forage. Intolerance is assessed as low. Recoverability is likely to be high (see Additional Information section below). | ||||
Tolerant | Not relevant | Not sensitive | Not relevant | |
Gobius couchi is likely to be tolerant of a decrease in water flow rate. | ||||
No information | No information | No information | Not relevant | |
Insufficient information was available to assess the sensitivity of Gobius couchi to an increase in temperature. | ||||
Intermediate | High | Low | Moderate | |
Temperature and oxygen levels change drastically over a tidal cycle in a rockpool. Couch's goby is capable of tolerating temperatures less than 6 °C by falling into a torpid state underneath stones (Minchin, 1988). By falling into this torpid state its ability to forage for food and reproduce is reduced. The geographical distribution of Gobius couchi is restricted to the south-west of England and the Mediterranean Sea. A temperature decrease is likely to have an impact on Gobius couchi. During the severe winter period in 1962-63 the south-west coast of Britain experienced temperatures 5 and 6 °C below the long-term average for about 2 months. During this period there was heavy mortality of observed populations of Gobius paganellus, Gobius minutus, and Gobius flavens (Crisp (ed.), 1964). Therefore a decrease in temperature may affect populations in the British Isles, by either shifting the geographical distribution further southwards towards warmer waters, or killing a proportion of the northern-most population. Intolerance has been assessed as intermediate. Recoverability is likely to be high (see Additional Information section below). | ||||
Low | High | Low | Moderate | |
An increase in turbidity would lead to a reduction in the amount of light penetration and, subsequently, a decrease in algal growth. Algae is the preferred food source of Gobius couchi, but other food sources (such as crustaceans and polychaetes) would still be readily available. The minimum light intensity needed for the detection and recognition of food are of great importance in many species of fish (Kinne, 1970). For instance if the organism needs to spend more time foraging for food, its energy expenditure will increase and could possibly lead to growth and reproductive problems. In heavily turbid waters fish larvae have been noted to show a greater than normal mortality. It is probable that Gobius couchi would be intolerant of changes in turbidity on a large scale, but probably not with changes of approximately 50 mg/l over a month. Therefore the species intolerance to turbidity is recorded as low. Recoverability is likely to be high (see Additional Information section below). | ||||
Tolerant* | Not relevant | Not sensitive* | Not relevant | |
Decreases in turbidity benefit algal growth and therefore more food (algae and associated crustaceans) would be readily available. This would be beneficial to the population and tolerant* has been suggested. | ||||
Tolerant | Not relevant | Not sensitive | Low | |
Faria & Almada (1999) found that when rocky intertidal fish were removed or added to pools which had been disturbed by storms (which move large quantities of sand and reshape their contents) the negative effects on populations were variable. However, storms are an extreme event and couch's goby is sufficiently mobile and able to shelter in rock crevices or move to deeper water. Therefore, a change of two ranks on the wave exposure scale is unlikely to affect the goby. | ||||
Tolerant | Not relevant | Not sensitive | Low | |
A reduction of two ranks on the wave exposure scale is unlikely to affect the goby. | ||||
No information | Not relevant | No information | Not relevant | |
Insufficient information. | ||||
Low | High | Low | Low | |
Fish generally forage for food using visual methods and can detect differing levels of light and shade. It is therefore probable that Gobius couchi can also detect these changes and would be slightly affected by activity on the shore, more so in the breeding season. However, periods of time when activity might be reduced due to hiding would most likely be slight. Intolerance to visual presence is recorded as low. Recoverability is likely to be high (see Additional Information section below). | ||||
Not relevant | Not relevant | Not relevant | Not relevant | |
Gobius couchi is sufficiently mobile to avoid abrasive contact and to shelter from it, therefore it is unlikely to suffer from abrasion. | ||||
Low | High | Low | Moderate | |
If displaced onto other suitable substrata no effects on the population are expected. Faria & Almada (1999) reported that experiments on removal and addition of individuals of Gobius cobitis show that the number of fish in the pools return to normal after a few weeks. It is likely that this would follow for Gobius couchi. However, if this occurs during the breeding season negative effects could be noted. Furthermore, if a male that is protecting fertilized eggs is displaced, the eggs are not likely to survive. Therefore, a low intolerance has been recorded. Recoverability is likely to be high (see Additional Information section below). |
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
Intermediate | High | Low | Low | |
The population decline of Gobius couchi in the Helford area was suggested to possibly be due to TBT pollution (Potts & Swaby, 1991) or other man-made sources. Lindane is likely to bioaccumulate significantly and is considered to be highly toxic to fish (Cole et al., 1999). Ebere & Akintonwa (1992) conducted experiments on the toxicity of various pesticides to Gobius sp. They found Lindane and Diazinon to be very toxic, with 96 hr LC50s of 0.25 µg/l and 0.04 µg/l respectively. TBT is very toxic to algae and fish. However, toxicity of TBT is highly variable with 96-hr LC50 ranging from 1.5 to 36 µg/l, with larval stages being more intolerant than adults (Cole et al., 1999). PCBs are highly persistent in the water column and sediments, have the potential to bioaccumulate significantly and can be very toxic to marine invertebrates. However their toxicity to fish is not clear (Cole et al., 1999). Therefore, an intermediate intolerance has been recorded. Recoverability is likely to be high (see Additional Information section below). | ||||
High | High | Moderate | Low | |
Cadmium, mercury, lead, zinc and copper are highly persistent, have the potential to bioaccumulate significantly and are all considered to be very toxic to fish (Cole et al., 1999). Mueller (1979) found that in Pomatoschistus sp., a different species of goby, very low concentrations of cadmium, copper and lead (0.5 g/l Cd2+; 5 g/l Cu2+; 20 g/l Pb2+) brought about changes in activity and an obstruction to the gill epithelia by mucus. This may also be true for Gobius couchi. Inorganic mercury concentrations as low as 30 µg/l (96-h LC50) are considered to be toxic to fish, whereas organic mercury concentrations are more toxic to marine organisms (World Health Organisation, 1989, 1991). Therefore, a high intolerance to heavy metals has been recorded. Recoverability is likely to be high (see Additional Section below). | ||||
Intermediate | High | Low | Low | |
Toxicity of low molecular weight poly-aromatic hydrocarbons (PAH) to organisms in the water column is moderate (Cole et al., 1999). They have the potential to accumulate in sediments and, depending on individual PAH, to be toxic to sediment dwellers at levels between 6 and 150 µg/l (Cole et al., 1999). The toxicity of oil and petrochemicals to fish ranges from moderate to high (Cole et al., 1999). The main problem is due to smothering of the intertidal habitat. Bowling et al. (1983) found that anthracene, a PAH, had a photo-induced toxicity to the bluegill sunfish. In fact, they reported that when exposed to sunlight anthracene was at least 400 times more toxic than when no sunlight was present. According to Ankley et al. (1997) only a subset of PAH's are phototoxic (fluranthene, anthracene, pyrene etc.). Effects of these compounds are destruction of gill epithelia, erosion of skin layers, hypoxia and asphyxiation (Bowling et al., 1983). It is possible that Gobius couchi could be similarly intolerant of hydrocarbons, however this is not known. An intermediate intolerance to hydrocarbons has been recorded. Recoverability is likely to be high (see Additional Information section below). | ||||
Intermediate | High | Low | Very low | |
Kinne (1984) reported that for the marine goby, Chasmichthys glosus, doses of as little as 100 rad (type not known) produced a readily observable response, causing severe damage to gonads of both males and females. The testes showed slightly greater intolerance. It is probable that Gobius couchi would respond similarly to sublethal irradiation at levels indicated above. Therefore an intermediate intolerance to radionuclides has been recorded. Recoverability is likely to be high (see Additional Information section below). | ||||
Low | High | Low | Low | |
Higher nutrient levels may encourage the growth of algae such as Ulva spp., which is an important food source for Gobius couchi. In comparison, a decrease in nutrient levels may lead to a decrease in the availability of green algae. However, this is likely to exert a slight effect on the couch's goby as it is able to ingest other types of food (such as crustaceans and polychaetes). Therefore, a low intolerance to nutrients has been recorded. Recoverability is likely to be high (see Additional Information section below). | ||||
Low | High | Low | Very low | |
No information is available for salinity effects on Couch's goby. However they do inhabit a wide range of habitats, with varying salinities. This implies that they are able to adapt reasonably well to various salinities. | ||||
Low | High | Low | ||
No information is available for salinity effects on Couch's goby. However they do inhabit a wide range of habitats, with varying salinities. This implies that they are able to adapt reasonably well to various salinities. | ||||
Low | High | Low | Very low | |
Temperature and oxygen levels change drastically over a tidal cycle in a rockpool. It is likely that Gobius couchi is adapted to these changes, but that a drastic long term decrease in oxygen levels would be expected to have a slight negative impact on the population. Oxygenation intolerance is assessed as low. Recoverability is likely to be high (see Additional Information section below). |
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
No information | Not relevant | No information | Not relevant | |
Insufficient Information. | ||||
Tolerant | Not relevant | Not sensitive | Not relevant | |
No alien or non-native species are known to affect Gobius couchi in Britain and Ireland. | ||||
High | Moderate | Moderate | Low | |
Gobius couchi has a restricted distribution, and is a rare and protected species. Therefore extraction of this species would have a great impact on the population density and viability. Intolerance is recorded as high, and recoverability is recorded as moderate (see Additional Information section below). | ||||
Tolerant | Not relevant | Not sensitive | Not relevant | |
Gobius couchi is not known to depend on any other species. Therefore, it is likely to be not sensitive to the extraction of other species. |
Wildlife & Countryside Act | Schedule 5, section 9 |
Features of Conservation Importance (England & Wales) |
National (GB) importance | Not rare/scarce | Global red list (IUCN) category | - |
Native | - | ||
Origin | - | Date Arrived | Not relevant |
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OBIS (Ocean Biodiversity Information System), 2023. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2023-03-30
This review can be cited as:
Last Updated: 04/05/2005