Chances are pike probably will now be present in the Quays, although none were stocked of course, heres a bit of interest from a 2001 survey
Salford Quays revisited - The impacts of fish introductions on
water quality 1987 to 2001, a fifteen year data-set
Keith Hendry, John Rebbeck, Bill Bellamy, Kevin Nash and Adrian E. Williams
APEM Ltd, Enterprise House, Manchester Science Park, Manchester M15 6SE, United Kingdom
Salford Quays, was isolated from the grossly polluted Ship Canal in May 1987 and an artificial mixing system (Helixors) introduced several months later to prevent thermal stratification and associated anoxia. The 8 hectares of enclosed water were effectively devoid of fish life prior to implementation of this combined management strategy. However, by 1989 water quality had improved dramatically allowing introduction of a variety of species including roach, perch, rudd, bream, carp, dace, tench and chub. The stocking was extremely effective with good survival, high growth rates and eventually successful spawning and recruitment of several species following introduction of artificial spawning media and macrophytes on appropriate structures. Hence, a range of species and age classes with a variety a feeding strategies, notably zooplanktivors, were present.
Following isolation in 1987, algal blooms, dominated by the cyanobacteria Oscillatoria agardhii became a common feature in the Quays. Over the next few years chlorophyll a concentrations increased relentlessly peaking at over 300 mg/ml. Several algal control techniques were investigated including intermittent destratification, barley straw and bio filtration using the freshwater mussel Dreissena polymorpha, but none were successful in effectively reducing the blooms. However, during the late 1990?s algal biomass began to gradually reduce. Chlorophyll a concentrations are dramatically lower, mean values of less than 40 mg/ml being recorded throughout the seasons for the past four years.
Using a 15-year data set, the paper examines the relationship between algal biomass, nutrient concentrations, bottom water oxygen concentrations and fish abundance at Salford Quays. It concludes that the main influence on the development of troublesome algal blooms was water column phosphorus, possibly augmented by sediment releases during low oxygen bottom water phased immediately following isolation in the late 1980?s. Subsequently maintenance of oxygen rich conditions has resulted in an overall reduction in available phosphorous leading to the long-term reduction (10 years) in algal concentrations observed. The work challenges the assumptions from studies elsewhere, notably the Norfolk Broads, that fish introductions promote algal blooms and hence compromise previously macrophyte-dominated systems. Conversely, the rational behind fish removal as a still water restoration strategy is called into question.
