Microsmatic fish are represented by numerous freshwater and marine species in which the well developed visual system provides most of the behavioural responses in comparison with the less developed chemosensory system. Visually guided diurnal or twilight predators as well as visually guided bentivorous and planktivorous species form this group of fish. The chemosensory system of microsmatic fish is active in providing their reproductive behaviour, social behaviour, spatial migration, partially anti-predator behaviour and is weak or indifferent in providing feeding responses.

Here, we consider esociform fish.

Esocidae

5 species: Esox americanus, E. lucius, E. masquinongy, E. niger, E. reicherti

Fresh waters of boreal Eurasia and Northern America

Northern pike, E. lucius, and other representatives of Esox genus, including Amur pike, E. reicherti, and some North American species, are apexpredators with the well developed vision and lateral line system.

According to data received by Devitsyna & Malyukina (1977) in the electrophysiological experiments, the olfactory system of pike, E. lucius, responds only to conspecific sexual pheromones (gonad extracts), but does not respond to conspecific odors, pure water and feeding substances like fish blood or tissue extracts. In feeding behaviour, musky, E. masquinongy, use vision and seismosensory system (New et al., 2001).

Pike larvae decrease the frequency of their attacks on zooplankters and show other anti-predator responses to chemical cues of Eurasian perch, Perca fluviatilis (Lehtiniemi, 2005; Lehtiniemi et al., 2005). It is also shown that pike are attracted by alarm pheromone of fathead minnow, Pimephales promelas (Mathis et al., 1995; Chivers et al., 1996; indirect data by Wisenden & Thiel, 2001).

Dalliidae

3 species: Dallia admirabilis, D. delicatissima, D. pectoralis

Fresh waters of Bering Sea basin

Blackfish primarily feed on crustacens (ostracods, cladocerans, copepods) and insect larvae (ephemeropterans, hemipterans, dipterans, odonates), with the occasional cannibalism and consumption of juvenile pike, E. lucius (Chlupach 1975).

However, leading sensory systems in feeding and reproductive behaviours of blackfish are unknown.

In winter with the oxygen lack, blackfish concentrate in the vicinity of holes in the ice, being easy to capture with the simple funnel-shaped traps made from strips of tamarack or spruce (Andersen et al., 2004). In spring and fall, blackfish are also easily caught while migrating to and from their summer habitats by placing the traps in narrow channels, it is appear these traps are not baited.

Umbridae

4 species: Novumbra hubbsi and Umbra krameri, U. limi, U. pygmaea

Fresh waters of Europe and Northern America

According to rare observations, feeding behaviour of mudminnows is rather provided by vision. For example, European mudminnow, U. krameri, eat in an aquarium only living and moving invertebrates such as cladocerans, copepods, Chaoborus larvae, chironomid larvae, culicid larvae, mayflay larvae, Acellus aquaticus and tubificid worms (Kováč, 1997). Cannibalism and hunting on juvenile fish in the nature are occasionally observed. However, Glasgow & Hallock (2009) report that Olimpic mudminnows, Novumbra hubbsi, are caught by the minnow traps baited with the chironomid larvae baits (15 g of chironomid larvae per one funnel-shaped trap). So, the problem of sensory providing of feeding behaviour in mudminnows is currently unclear.

On the other hand, chemical cues may play an important role in social and anti-predator behaviours of mudminnows. Indeed, central mudminnows, U. limi, demonstrate anti-predator behaviour in response to conspecific chemical alarm cues (Wisenden et al., 2007). Yet, mudminnows display comlex reproductive behaviour, from territory guarding to parental care (Hagen et al., 1972; Bohlen, 1995; Kováč, 1997). Reproductive behaviour of mudminnows must be supported by chemical cues, another problem that awaits further investigations.

Perhaps, blackfish and mudminnows must be considered as mediosmatic fish.

Basic References

Andersen D.B., Brown C.L., Walker R.J., Elkin K. 2004. Traditional ecological knowledge and contemporary subsistence harvest of non-salmon fish in the Koyukuk River drainage, Alaska. U.S. Fish and Wildlife Service, Final Report for Study 01-100-3, 164 p.

Bohlen J. 1995. Laboratory studies on the reproduction of the European mudminnow (Umbra krameri Walbaum), 1792. Annalen des Naturhistorischen Museums in Wien 97, 502-507

Chivers D.P., Brown G.E., Smith R.J.F. 1996. The evolution of chemical alarm signals: attracting predators benefits alarm signal senders. The American Naturalist 148, 649-659

Chlupach, R.S. 1975. Studies of introduced blackfish in waters of southcentral Alaska. Annual Performance Report for Sport Fish Studies, volume 16, study G-II-K. Alaska Department of Fish and Game, 62-78

Devitsyna G.V. 1977.  Comparative study of the olfactory analyser morphology in fishes. Journal of Ichthyology 17, 129-139

Glasgow J., Hallock M. 2009. Olympic mudminnow (Novumbra hubbsi) in the Green Cove Creek Watershed, Thurston County, Washington: Distribution and recommendations for protection. Washington Department of Fish and Wildlife, 18 p.

Hagen D.W., Moodie G.E.E., Moodie P.F. 1972. Territoriality and courtship in the Olympic mudminnow (Novumbra hubbsi). Canadian Journal of Zoology 50, 1111-1115

Kováč V. 1997. Experience with captive breeding of the European mudminnow, Umbra krameri Walbaum, and why it may be in danger of extinction. Aquarium Sciences and Conservation 1, 45-51

Lehtiniemi M. 2005. Swim or hide: predator cues cause species specific reactions in young fish larvae. Journal of Fish Biology 66, 1285–1299

Lehtiniemi M., Engström-Öst J., Viitasalo M. 2005. Turbidity decreases anti-predator behaviour in pike larvae (Esox lucius). Environmental Biology of Fishes 37, 1-8

Mathis A., Chivers D.P., Smith R.J.F. 1995. Chemical alarm signals: predator detterents or predator attractants? The American Naturalist 145, 994-1005

New J.G., Fewkes L.A., Khan A.N. 2001. Strike feeding behavior in the muskellunge, Esox masquinongy: contributions of the lateral line and visual sensory systems. Journal of Experimental Biology 204, 1207-1221

Wisenden B.D., Thiel T.A. 2001. Field verification of predator attraction to minnow alarm substance. Journal of Chemical Ecology 28, 417-422

Wisenden B.D., Karst J., Miller J., Miller S., Fuselier L. 2007. Anti-predator behaviour in response to conspecific chemical alarm cues in an esociform fish, Umbra limi (Kirtland 1840).  Environmental Biology of Fishes 82, 85-92