Comparison of coarse‐resolution rapid methods for assessing fish passage at riverine barriers: ICE and SNIFFER protocols

Abstract

Man-made barriers have led to river fragmentation, restricting fish migrations to critical habitat. Fragmentation is relevant to the Water Framework and Habitats (Annex II fish) Directives of the European Union. SNIFFER (Water Framework Directive 111) is a United Kingdom-developed fish passability assessment method with passability scores based on published data describing the physiological abilities of different fish species/life stages. SNIFFER is an objective protocol, but final scores require assessor opinion on specific nonquantified elements. The French ICE fish passability assessment protocol covers a larger number of fish species/life stages and removes the requirement for velocity readings (except in a few situations) and expert opinion with assessors following a decision tree process. In most situations, fewer direct measurements are required for the ICE protocol, and the evaluation process is quicker and simpler. Both protocols utilize a similar passability scoring system (0 = total barrier, 0.3 = high impact, 0.6 = low impact, 1 = no risk). Comparison of outcomes for species categories for both protocols was made in paired comparisons for 112 transversal sections (fish passage routes) recorded at 52 barriers (in-river structures) of varying complexity in Irish rivers. Overall scores were found to be in high agreement for species groups at impassable (Score 0) and no risk (Score 1) barriers. Protocol agreement dropped significantly for high-impact (Score 0.3) and low-impact (Score 0.6) barriers.Results are discussed in the context of barrier passability at the 52 structures examined, primarily in the context of Atlantic salmon (Salmo salar L.) and of sea lamprey (Petromyzon marinus L.). In total, 22 of the structures had one or more fishways or fish passage solutions built into them as part of the original design. Both protocols identified substantial problems for sea lamprey and adult salmon at the majority of the fish passage solutions surveyed. The merits and shortcomings of both protocols, for managers assessing fish passability at complex riverine structures, are discussed.

Are national barrier inventories fit for stream connectivity restoration needs? A test of two catchments

“…Since the context of our study was from a longitudinal connectivity restoration viewpoint, particularly as regards fish passage, we recorded obstacles that had the potential to limit upstream movement of fish at normal to low flows (~Q 50 –Q 90 ), while acknowledging that maintaining free downstream‐migration passage is also important (Silva et al , 2018). Obstacles to the free movement of fishes depend on obstacle characteristics (especially height and gradient), fish species and environmental conditions (Kemp and O'Hanley, 2010; Barry et al ., 2018). In our surveys, any artificial structure having a vertical or steeply sloping (>45°) step, exceeding 0.2 m in height, was regarded as a potential obstacle to weakly swimming taxa (Utzinger et al , 1998; Tummers et al , 2016).…”

Identifying spawning sites and other critical habitat in lotic systems using eDNA “snapshots”: A case study using the sea lamprey Petromyzon marinus L.

“…A gravel trap installed at Blackboys Bridge ( Figure 1) is a vertical impediment to upstream fish migration which has a Deniltype fish pass installed. This trap, as well as the Annacotty weir, was recorded as "impassable" to sea lamprey, in the prevailing conditions at the time of study, in a WFD SNIFFER (2010) fish passage assessment (Barry, Coghlan, Cullagh, Kerr, & King, 2018). The Annacotty weir is the most significant structure that may impede sea lamprey passage in this system, however, within 2 km upstream of this structure, migrants also encounter a crump weir fish counter and the remnants of a weir breached to permit sediment transport and fish passage.…”

“…Two major weirs are present in the lower part of the main stem. Clondulane Weir is located 25 km upstream of the tidal limit (between MBW09 and MBW10; Note that MBW11 and MBW 12 are at the tidal limit hydraulic head difference of 2.5 m. Both structures were assessed as "Impassable" to sea lamprey in the prevailing conditions, using the SNIFFER (2010) or WFD 111 protocol (Barry et al, 2018). Evidence from previous spawning surveys has indicated significant P. marinus spawning effort downstream of both structures (Inland Fisheries Ireland, 2010; King & Linnane, 2004) and has shown that some degree of passage upstream of the first weir (Clondulane) can occur in years with higher flows (King & Linnane, 2004;IFI, unpublished data…”

“…Note that MBW11 and MBW 12 are at the tidal limit hydraulic head difference of 2.5 m. Both structures were assessed as "Impassable" to sea lamprey in the prevailing conditions, using the SNIFFER (2010) or WFD 111 protocol(Barry et al, 2018). Both are intact, full-channel width structures with F I G U R E 2 Map of the Munster Blackwater Catchment (MBW) in southern Ireland showing the location of all 12 sampling sites along the main stem of the river as well as barriers to migration.…”

Passage Performance of Potamodromous Cyprinids over an Experimental Low-Head Ramped Weir: The Effect of Ramp Length and Slope

“…River fragmentation by small engineered structures, far more numerous than dams, has led to severe declines or local extinctions of many fish populations by blocking upstream movements for reproduction, feeding, and refuge needs [1][2][3]. By identifying the importance of aquatic connectivity for good ecological quality in rivers, the European Water Framework Directive (WFD) emphasized the need to re-establish free movements for all fish species and size classes, regulating that member states should assess all instream obstacles, even small weirs, and minimize their barrier effect [4][5][6]. Since then, a few studies on small obstacles (considering assessment protocols, e.g., [7][8][9], or field assessments, e.g., [10][11][12]) and projects, such as the European project AMBER and other operational programs like the EU LIFE programs, have been developed, aiming to enhance the knowledge on permeability of small obstacles and fish passage, recommend strategies for action, and rehabilitate river habitats [3,13,14].…”