Fish pass design - criteria for the design and approval of fish passes and other structures to facilitate the passage of migratory fish in rivers

Many of British rivers hold stocks of salmon (Salmo salar L.) and sea trout (Salmo trutta L.) and during most of the year some of the adult fish migrate upstream to the head waters where, with the advent of winter, they will eventually spawn. For a variety of reasons, including the generation of power for milling, improving navigation and measuring water flow, man has put obstacles in the way of migratory fish which have added to those already provided by nature in the shape of rapids and waterfalls. While both salmon and sea trout, particularly the former, are capable of spectacular leaps the movement of fish over man-made and natural obstacles can be helped, or even made possible, by the judicious use of fish passes. These are designed to give the fish an easier route over or round an obstacle by allowing it to overcome the water head difference in a series of stages ('pool and traverse' fish pass) or by reducing the water velocity in a sloping channel (Denil fish pass). Salmon and sea trout make their spawning runs at different flow conditions, salmon preferring much higher water flows than sea trout. Hence the design of fish passes requires an understanding of the swimming ability of fish (speed and endurance) and the effect of water temperature on this ability. Also the unique features of each site must be appreciated to enable the pass to be positioned so that its entrance is readily located. As well as salmon and sea trout, rivers often have stocks of coarse fish and eels. Coarse fish migrations are generally local in character and although some obstructions such as weirs may allow downstream passages only, they do not cause a significant problem. Eels, like salmon and sea trout, travel both up and down river during the course of their life histories. However, the climbing power of elvers is legendary and it is not normally necessary to offer them help, while adult silver eels migrate at times of high water flow when downstream movement is comparatively easy: for these reasons neither coarse fish nor eels are considered further. The provision of fish passes is, in many instances, mandatory under the Salmon and Freshwater Fisheries Act 1975. This report is intended for those involved in the planning, siting, construction and operation of fish passes and is written to clarify the hydraulic problems for the biologist and the biological problems for the engineer. It is also intended to explain the criteria by which the design of an individual pass is assessed for Ministerial Approval.

River Dart Weir and fish pass survey 1992

This is the River Dart, Weir and Fish Pass Survey 1992 report produced by the National Rivers Authority. It goes through the general condition of Weirs and fish passes to determine the extent of problems associated with the upstream and downstream migration of salmonids. It considers solutions where problems exist and investigates the exact use of the resource. It looks at the following Weirs: Totnes, Staverton, Hood, Kilbury, Buckfast, Holne, Mardle (River Mardle), Holybrook (Holybrook), Jordan (West Webburn), Swincombe Intake (River Swincombe), Blackbrook, West Dart, Cowsic (Devonport Leat), Kingfisher Press (Bidwell Brook) and Bagpark (East Webburn). It also contains location maps of the weirs and individual fact sheets along detailed pictures and diagrams.

New Weir and Fish Pass Whitendale in August 1951

Two men working in a weir and fish pass at Whitendale, North West England, UK. This photo is part of a Photo Album that includes pictures from 1935 to 1954.

Rooks fish pass at Garstang Weir in River Wyre

Rooks fish pass at Garstang Weir in the River Wyre, North West England, UK. This photo shows pollution in River Lune in July 1949. This photo is part of a Photo Album that includes pictures from 1935 to 1954.

New Weir and Fish Pass Whitendale in August 1951

Two men working in a weir and fish pass at Whitendale, North West England, UK. This photo is part of a Photo Album that includes pictures from 1935 to 1954.

Abbeystead Fish Pass in the River Wyre, 1949

Photo of a check trap in Abbeystead Fish Pass in the River Wyre in 1949. The River Wyre is located in the North West of England, UK. This photo is part of a Photo Album that includes pictures from 1935 to 1954.

Récentes variations de temperature et de salinité à Nhatrang (avec une Annexe des données des autres points fixes établis dans le passé)

The authors expose results of recent routine observations and those of oceanographic stations undertaken in 1957, at Nhatrang. They introduce also in the Note, results of others fixed observations-stations for comparisons.

Florida's West Coast inlets: shoreline effects and recommended action

This report responds to the 1986 Beaches Bill which, in recognition of the potential deleterious impact on Florida's beaches of inlets modified for navigation, mandated a study of those inlets with identification of recommended action to reduce the impacts. This report addresses west Coast inlets; East Coast inlets are the subject of a companion report. There are 37 inlets along that portion of Florida's West Coast commencing from Pensacola Bay Entrance to Caxambas Pass at the south end of Marco Island. Compared to those on the East Coast, most West Coast inlets have not had the deleterious effects on the adjacent beaches, yet all modified inlets without proper management have the potential of impacting unfavorably on the adjacent shorelines. Moreover, at present there is interest in opening three West Coast entrances which either have been open in the past (Midnight Pass) or which have opened occasionally (Navarre Pass and Entrance to Phillips Lake). A review of inlets in their natural condition demonstrates the presence of a shallow broad outer bar across which the longshore transport Occurs. These shallow and shifting bar features were unsuitable for navigation which in many cases has led to the deepening of the channels and fixing with one or two jetty structures. Inlets in this modified state along with inappropriate maintenance practices have the potential of placing great ero$ional stress along the adjacent beaches. Moreover. channel dredging can reduce wave sheltering of the shoreline by ebb tidal shoals and alter the equilibrium of the affected shoreline segments. The ultimate in poor sand management practice is the placement of good quality beach sand in water depths too great for the sand to reenter the longshore system under natural forces; depths of 12 ft. or less are considered appropriate for Florida in order to maintain the sand in the system. With the interference of the nearshore sediment transport processes by inlets modified for navigation, if the adjacent beaches are to be stabilized there must be an active monitoring program with commitment to placement of dredged material of beach quality on shoreline segments of documented need. Several East Coast inlets have such transfer facilities; however. the quantities of sand transferred should be increased. Although an evolution and improvement in the technical capability to manage sand resources in the vicinity of inlets is expected, an adequate capability exists today and a concerted program should be made to commence a scheduled implementation of this capability at those entrances causing greatest erosional stress on the adjacent shorelines. A brief summary review for each of the 37 West Coast inlets is presented including: a scaled aerial photograph, brief historical information, several items related to sediment losses at each inlet and special characteristics relevant to State responsibilities. For each inlet, where appropriate, the above infor~tion is utilized to develop a recommenced action. (PDF has 101 pages.)

Aktuelle Planungen zur Regelung der Beifangproblematik in der Krabbenfischerei

At present the fishery for the brown shrimp (Crangon crangon L.) is one of the most economically rewarding fisheries in Europe. Due to the small size of the target objects this fishery has to be carried out with rather small meshes. As it is, however, performed on the nursing grounds of important fish species it encounters a severe bycatch problem. On this basis, EU Council regulation 850/98 demands the use of either sieve nets or sorting grids from 1 July, and to pass pertaining national bye-laws. Germany discusses to use either sieve nets of 70 mm mesh opening or sorting grids of 20 mm bar distance, and tries to achieve a harmonization of the byelaw with neighbouring countries of The Netherlands and Denmark to ensure equal conditions on the same fishing grounds.

Media of communication among fishermen around Kainji Lake basin

The findings are presented of a study conducted in the framework of the Nigerian-German Kainji Lake Fisheries Promotion Project to examine the role and structure of communication in fishing villages around Kainji Lake in Nigeria. The major aim was to be able to utilize the knowledge at a later stage in the project cycle to pass on fisheries extension messages to fishing communities. The study had the following terms of reference: 1) describe the structure and processes of communication of fishermen around Kainji Lake; 2) identify the formal and informal media of communication used by the fishermen to communicate information concerning their job; 3) describe the problems inhibiting usage of the different media identified; 4) ascertain the extent of use of mass media by fishermen around the lake; and, 5) identify acceptable ways by which fisheries information can be repackaged for the use of extension workers. (PDF contains 58 pages)

Pathways for the uptake of dissolved organic matter (DOM) by aquatic animals

In this article, pathways from freshwater and marine environments are described. DOM is defined operationally as all the organic compounds which pass through a filter of pore size 0.45 microm., those retained on the surface of the filter being particulate organic matter (POM). DOM can be taken up directly by animals by transfer across the body wall, but more commonly DOM is obtained from ingested food. Once ingested POM from food particles are broken down in the gut, small molecules of DOM are released for transfer across the gut wall. Some ingested particles are attacked by micro-organisms living in the gut, thereby making the DOM available to the host animal. The importance of the microbial loop is discussed, as well as aggregation processes between the fractions of DOM which are more obviously particulate in nature. (DBO)

The life capacity of copepod's eggs passed through the gut of Ladoga lake Coregonus [Translation from: Zool.Journal.Moscow 29-5, 476-477, 1950]

This short paper summarises findings of experiments that were carried out using copepod eggs taken from guts of Coregonus which breeds in various Ural lakes. The study showed that copepod eggs can pass through the gut of Coregonus unharmed.

Polyculture du machoiron Chrysichthys nigrodigitatus avec Oreochromis niloticus en etang

Fingerling catfish Chrysichthys nigrodigitatus (P=4.0 g, FL=65.3 mm) and Oreochromis niloticus (P=11.2 g, TL=84.8 mm) were stocked in 0.06 ha earthen ponds at Pass (Annex of the Aquaculture Research Station at Layo, Côte d'Ivoire). The ponds were stocked at densities of 6700 catfish per ha, and 6700 catfish with 3350 tilapias per ha. The study lasted from February to August 1985 and the fish were fed daily at 6% of the estimated catfish biomass with 32% protein pellet. There were no differences in mean weekly water temperature (p > 0.05). The dissolved oxygen concentration was higher in ponds where tilapias were added (p < 0.05) The presence of tilapias seems to have improved water quality and did not affect growth and production of catfish (p > 0.05). Their presence also significantly increased total fish yield (p < 0.05) by 23.5%. There were no significant differences (p > 0.05) in catfish survival between the two production systems.

Electric fishing survey of the gravel addition sites on the River Wyre, Grizedale Beck and Joshua's Beck.

Although geographically the River Wyre lies between two rivers containing major migrations of adult salmon and sea trout, its rod & line fisheries have for a number of years produced exceptionally low catches. In order to determine the causes of this the Wyre Salmon and Sea trout Restoration Group (WSSRG) was conceived in 1994 as a partnership between the then National Rivers Authority (now Environment Agency), local landowners, angling clubs and interested parties. Two studies of 1994 and 1995 stated that there is a shortage of useable spawning gravels on the river. This is compounded by Abbeystead Reservoir acting as a gravel trap, the siltation of gravels on several side becks and problems with access to available gravels by returning adults. There was also perceived to be a need for accurate fishery data from the river encompassing redd counts, catch data and surveys of fry populations. The 1995 report suggested a number of management proposals which might be adopted in order to improve and create available spawning habitat for migratory salmonids. Funding was made available to create three spawning gravels on each of two side becks (Grizedale Beck and Joshua's Beck) and the addition of gravels to a site oh the main river below Abbeystead Reservoir. Modifications were also made to the fish pass at Abbeystead to allow easier passage of fish. These improvements were made in the autumn of 1995. Salmonid spawning redd counting was undertaken on the whole Wyre catchment in 1995/1996 and specific surveys by electric fishing on the gravel enhancement sites in the summer of 1996. This report details the current state of the improvement works that were undertaken and presents the results of electric fishing surveys in September 1996. A number of lessons have been learnt which will be of great benefit to the Fisheries Function in other parts of the Wyre catchment and the Central Area in general.