Introduction

There are approximately 70 fish taxa documented in British Columbia’s freshwater environment (Clemens and Lindsey 1959). Of those, 70 freshwater species, approximately 29 are resident or semi-resident in the waters in and around the City of Richmond, including Lulu Island (Naito 2004). These often occur in ditches, creeks and other wetland sites on Richmond’s dyked islands. Included amongst these are species at risk, economically important species and species of special interest for sportsmen such as salmon species. This range of species makes inventorying the fish species on Lulu Island in the vicinity of the Lulu Island Bog important.

The first European settlers in Richmond and on Lulu Island were farmers who immediately set about clearing, dyking and draining Lulu Island (City of Richmond 2005).  Dykes and drainage altered the distribution and nature of aquatic habitats on Lulu Island. Natural streams and sloughs that existed prior to settlement disappeared or were modified, replaced by a growing network of drainage channels flowing into the Fraser River to control the island’s water levels and prevent flooding. Aquatic habitats in and around Lulu Island today primarily consist of this network of drainage channels and those outside the dyke associated with the Fraser River estuary (Naito 2004). 

Lulu Island is divided into drainage catchments, each of which drains the network of waterways contained therein. Each drainage catchment is defined by the area that is contributing drainage to the associated water control structure under gravity conditions (Paller, pers. comm. 2005). 

The catchments are drained by water control structures whose design and function vary. All of the catchments’ water control structures allow water to flow out into the Fraser River via gravity. Lulu Island does have varying elevation. Approximately one quarter of Lulu Island is 5 metres or more above sea level, and the remaining three quarters are lower (Kidd 1979) (see ******** elevation map).

Most catchments have water control structures with one-way gates that are also designed to prevent the inflow of water from the Fraser River. However, there are a number of catchments with structures that are capable of opening to allow water in for irrigation from the Fraser River via gravity at high tide, and this has implications for the fish fauna of Lulu Island. The Number 8 Road North catchment is capable of pumping water in from the Fraser River in addition to allowing it in and out via gravity (Figure   ***).  The pump intake is screened to prevent the uptake of debris or fish.

Figure ___ :   Lulu Island Drainage Catchments and Salmonid Habitat (Source__)

The Lulu Island Bog is drained by four catchments: Bath Slough; Highway 99; Shell Road North; and Number 4 Road North (see Figure ___??) , none of which are designed to facilitate water intake. However, in general, catchments are not isolated from one another. Pipes and/or open channels may connect adjacent catchments, allowing water to flow between catchments in the event of blockage, conveyance system overcapacity, pump settings or water level control structures within a given catchment (Paller, pers. comm. 2005). These interconnections minimize the risk of flooding, but also allow fish to make their way through the interconnecting systems. Waterways in the catchments consist of open channels or ditches and buried pipes and culverts.

Although some of the waterways immediately surrounding the bog are open channels, a significant portion of the waterways in the four catchments that drain the bog that are enclosed (Naito pers. comm. 2004).

To date,there has been very little inventory of the fish species present in Lulu Island’s waterways.  Two consulting firms, Beak Consultants and Integrated Resource Consultants (IRC), surveyed the Number 7 Road North, Cambie Road, and Number 8 Road North irrigation ditches on behalf of the City of Richmond in 1993 and 1994, respectively. (Beak Consultants 1993) (IRC 1994). These surveys recorded the presence of salmonids in the Cambie Road and Number 8 Road North irrigation ditches (Beak Consultants1993) (IRC 1994). DFO Habitat Biologist Brian Naito has also mapped the waterways on Lulu Island that may be potentially salmon-bearing based on the anticipated water quality (particularly in the springtime when salmonids are most likely to be present) and likelihood of their survival (see Figure   ***).  Extended lengths of enclosed waterways may decrease the likelihood of salmonid presence; past studies have shown fish to be less likely to move through enclosed waterways than open waterways (Warren and Pardew 1998).

Several different aquatic habitats are present in and around the Lulu Island bog. In the DND property, a small fen contains seasonal free-standing flowing water (Rose- you’ll have to be a source here if you feel this should read as “flowing water”- I never saw any water flow, only standing water in a depression). There is a small, manmade pond in the southeast corner of the Richmond Nature Park (RNP west) and another manmade pond in the Richmond Nature Study Area (RNP east). All three bog properties also have peripheral drainage ditches which are dry in some summers and wet from precipitation and road runoff later in the fall, winter and early spring. There are also two larger drainage ditches that contain water throughout the year. They are located on the east side of the Richmond Nature Park (RNP west) and the west side of the Richmond Nature Study Area (RNP east), and were built in the late 1950s in conjunction with the construction of Highway 99 which bisected the park’s west and east properties.

Purpose

There has been no previous known effort to survey for fish species in and around the Lulu Island Bog. This study aimed to carry out a presence/not detected survey of the open aquatic habitats of the Lulu Island bog for the presence of fish species. A literature search on drainage systems, significant species, and potential for fish occurrences was conducted. Particular attention was paid to the potential for occurrence of Red or Blue-listed species, or significant species such as salmonids.  Water bodies were assessed for standing water and suitability during the dry season, and later during the wet season. Based on the seasonality of water presence, connectivity to other waterbodies and the amount of standing water, three ditches were targeted for sampling: the west ditch of the west park property, and the larger ditches located on the east side of the west property and the west side of the east property.  The ditches surrounding the DND property did not contain sufficient standing water during the survey period and were not sampled.

Methods

In inventorying for fish species of the Lulu Island Bog and perimeter ditches, a literature search was conducted, local Department of Fisheries and Oceans (DFO) officials were contacted, and fish sampling was carried out in targeted areas using standard fish sampling procedures.

Based on the results of a literature search on recorded species in the area (Naito 2004), habitat preferences, and the connectivity of Lulu Island waterways, several species were targeted in the fish survey:

1) Brassy Minnow (Hybognathus hankinsoni)

BC Status: Yellow-listed

At the outset of the inventory, the Brassy Minnow (Hybognathus hankinsoni) was Blue-listed (MELP 2004) and identified as an intermediate priority candidate for assessment on the COSEWIC candidate list (COSEWIC 2004). Recent surveys in the northern part of its B.C. range recorded a distribution more widespread than previously established. As a result of these surveys, its status was reassessed in 2004, and it is now Yellow-listed (MSRM 2004). The Brassy Minnow’s historical range includes the Fraser Lowland (BC Fish Facts 2004). They occur in small, weedy, slow moving creeks or streams with sand, gravel or mud bottoms. They can also be found in boggy lakes, sloughs, and ditches in brackish or in tidally influenced waters (BC Fish Facts 2004). Within Richmond, the Brassy Minnow occurs in the Fraser River (Northcote 1974). 

2) Coho salmon (Oncorhynchus kisutch)

BC Status: Yellow-listed

COSEWIC: Interior Fraser population- endangered

Coho salmon juveniles have been recorded in the Number 8 Road Irrigation Drainage Channel north of Highway 91 (IRC 1994), more than 5 kilometres from the study area. Juveniles will remain in their natal stream for up to a year before migrating out to the ocean.  These streams generally have small gravel substrate, low flow velocity and clean water.  In the winter, to avoid high water flows the juveniles will often migrate into smaller tributaries and off channel habitat. Ditches may offer habitat similar to low flow tributaries and off channel habitat, thus indicating need for inventorying the ditches around the bog.

3) Chinook salmon (Oncorhynchus tshawytcha)

BC Status: Yellow-listed

Chinook salmon (Oncorhynchus tshawytcha) juveniles have also been recorded in the Number 8 Road Irrigation Drainage Channel north of Highway 91, as well as the Cambie Road Irrigation Drainage Channel north of Highway 91 (Beak Consultants 1993) (IRC 1994). Chinook generally inhabit larger deeper tributaries than Coho. The juveniles will move from the main river stem into smaller tributaries and seek cover under overhanging vegetation and cutbacks in the fall and winter. The two larger ditches in the study area provide overhanging vegetation and low water velocity which may be suitable for Chinook juveniles, and thus were targeted for sampling.

Based on a literature search and input from a DFO fisheries biologist, the following sampling methodology was followed:

• Gee-type minnow traps were placed in three ditches surrounding the bog, in addition to other water level dependent locations
• 7 traps were placed in the east ditch on the west property
• 7 traps were placed in the west ditch on the east property
• 2-3 traps were placed in the west ditch on the west property 
• Traps were set daily for 1 week/month from July to November, with the exception of August and September
• When set, traps were checked every 4-5 hours.  Although they have a maximum allowable soak time of 24 hours (RISC Fish Collection Standards 1997), they were checked more frequently to prevent fish mortalities due to possible low oxygen levels and high temperatures.
• Traps were baited with cat food. The bait was placed in a nylon stocking and wired to the side of the trap or in a film canister with holes punched throughout.
• Small rocks were placed in the traps to provide refuge and minimize predation among captured fish (RISC Fish Collection Standards 1997)
• Each species trapped was photo documented and recorded.  Species of interest were measured and weighed.  Specimens were released after measurement.
• After each trapping period all traps were removed so that they did not continue to fish indefinitely (RISC Fish Collection Standards 1997)

Results

2168 trapping hours were expended between July and December 2004. Threespine stickleback (Gasterosteus aculeatus) and Goldfish (Carassius auratus) were the only two fish species recorded in adjacent ditches.  In total, 1082 Threespine Stickleback and 2 Goldfish were captured.

Table ____:  Fish species of the Lulu Island Bog

Species Accounts

Threespine Stickleback (Gasterosteus aculeatus)

Conservation Status:  not of concern

Habitat:  marine, brackish and freshwater; lakes, ponds, streams, and ditches

Comments:  Very widespread throughout BC.  In Richmond they have been found in the Number 7 Road Irrigation Drainage Channel north of Highway 91, Number 8 Road Irrigation Drainage Channel north of Highway 91, Cambie Road Irrigation Drainage Channel north of Highway 91, Nelson Road and Westminster Highway Drainage Channel, and Westminster Highway between Number 7 Road and Number 8 Road (Naito 2004).

Goldfish (Carassius auratus)

Conservation Status:  not of concern; a widespread introduced exotic species

Habitat:  prefer warm, shallow, muddy-bottomed lakes and ponds; spawn in weedy shallows (Carl et al. 1973)

Comments:  Goldfish were introduced to BC from Asia and have become widespread since their introduction.  In Richmond they have been found in the Nelson Road and Westminster Highway Drainage Channel, Westminster Highway between Number 7 Road and Number 8 Road, and Number 8 Road Irrigation Drainage Channel north of Highway 91 (Naito 2004).

Discussion

 The results of this survey are affected by survey design and methodology, and by the characteristics of the waters sampled.

In recognizing the former, it is important to acknowledge that the results of this survey do not prove the absence of species not detected. Some species are not effectively trapped using minnow traps, such as Brook Lamprey. Any fish larger than the trap entry would also be excluded from capture. The traps fished for four hour periods to minimize mortalities. This short fishing period may have limited fishing success. Traps were also set for only a portion of the year, which may not have coincided with the seasonal presence of additional species in the waterways surrounding the study area.

Several key characteristics of the waters sampled influence the presence, or recorded presence, of fish species in the ditches around the perimeter of the Lulu Island Bog, including connectivity, channel enclosure, water quality, seasonality of water flows, seasonality of surveys, and climatic flux. 

Connectivity

Connectivity of the study area waterbodies and their proximity to the Fraser River may both have an effect on fish species abundance and distribution. Salmonids, including Chinook and Coho Salmon and Cutthroat Trout, have been found in several irrigation drainage channels approximately 5 kilometres from the Richmond Nature Park.  Other freshwater species, including the Largescale Sucker, Common Carp, Goldfish, Redside Shiner, Pikeminnow, and Brown Bullhead have also been recorded in irrigation drainage channels (Naito 2004). Most of these species are recorded in drainage channels more proximal to the Fraser River than the study area. This may be due to a lack of surveys further inland, or there may be barriers or filters discouraging fish movement further from the river.

As mentioned, drainage catchments differentially allow water inflow and outflow. Drainage catchments that open to allow inflow are more likely to periodically or permanently host species from the Fraser River, as fish entry is presumably easier. However, catchments are not isolated from one another, and if suitable connecting habitat exists, fish may move between catchments. It is also possible for fish to directly enter catchments that do not open to allow inflow if they enter drainage control structures against the flow direction. The connectivity of the two year-round ditches where the trapped fish were caught is not well understood. The ditches are the jurisdiction of the provincial Ministry of Transportation, whose drainage channels link with the city’s drainage system (Smith, pers. comm. 2005). The two ditches appear to connect to city drainage channels at Number 5 Road.

Enclosed Channels

The degree to which drainage channels in a catchment are enclosed may have significant effects on fish movement. Warren and Pardew (1998) found that fish movement through culverts was an order of magnitude lower than through open box channels or natural stream reaches. Hence, the enclosed drainage channels on Lulu Island may restrict fish movement between more suitable open channel habitats. The drainage catchments that drain the Lulu Island Bog contain extended lengths of enclosed channels. This has several implications. First, it may prevent fish species that directly enter those drainage catchments from reaching the ditches in the study area. Second, it may prevent fish species from adjacent catchments from moving into the ditches in the study area. In other words, though connecting channels may exist between catchments draining the bog and catchments with aforementioned fish species, the connecting channels may be largely enclosed, and thus, effectively act as barriers between or within catchments.                                                                                                            

Water Quality

 The quality of the water in and around the Lulu Island bog may also play a role in the fish species composition in the study area.  The ditches are likely polluted by virtue of their urban and agricultural surroundings, which may make the water unsuitable for certain species. Dissolved oxygen content and water temperature are another two important factors that influence the suitability of aquatic environments for fishes (Hondzo and Stefan 1996) and may be pertinent in explaining the fish species composition in the study area.

Fish species have different tolerances to temperature and dissolved oxygen content. Beitinger et al. (2000) summarize research on the temperature tolerances of North American freshwater fishes. Threespine Stickleback and Goldfish and Hybognathus placitus (a relative of the Brassy Minnow) exhibit higher maximum temperature tolerances than salmonids such as Coho Salmon (Beitinger et al. 2000). During the summer months, the study area ditches may rise to sub-optimal or lethal temperatures for salmonids, but remain suitable for minnows (M.A. Whelen and Associates Ltd., as cited in Hebda et al. 2000), Threespine Stickleback and Goldfish. Increases in water temperature can lead to decreases in dissolved oxygen content (Morrill et al. 2005).  Dissolved oxygen levels below 6.0 mg/l can cause stress or death in juvenile salmonids (CCME 1992, as cited in Hebda et al. 2000) (Sigma Environmental Consultants 1983, as cited in Hebda et al. 2000).  Physical and chemical measurements in the Number 7 Road, Number 8 Road and Cambie Road irrigation ditches in 1993 and 1994 recorded low flow, water temperature as high as 23º C, dissolved oxygen content as low as 1.2 mg/L, and regular occurrence of dark leachate (Beak Consultants 1993) (IRC 1994). IRC (1994) stated that high temperatures (15 - 20º C) and low dissolved oxygen content (1.2 - 9.5 mg/L) in the Number 8 Road ditch during June and July likely caused stress in fish populations present. It is reasonable to assume that the climate and flow conditions in the study area are similar to those of the irrigation ditches surveyed in 1993 and 1994. Dissolved oxygen content and water temperature may also be similar, and thus, stresses on fish populations in the study area during warmer months due to water quality are a significant possibility.

Water flow in all of the study area ditches is very limited. There are no other apparent water mixing processes that might increase dissolved oxygen content in the water. The water volume in the ditches is limited, and in the two ditches that contain water throughout the year, water depth is shallowest during the summer. Consequently, water temperatures during hot spells in the summer months may become quite high and dissolved oxygen content may decrease to the point of causing stress or death in fishes. Although no measurements of water temperature and dissolved oxygen content were recorded for this study, trapping mortalities occurred only during July, not in the fall months. This further suggests that temperature and/or dissolved oxygen content are important factors in determining water quality in the study area ditches.

Seasonality of Water Flows

Salmonids and minnow, carp, or sculpin species may also not be present as a result of the seasonality of most of the perimeter ditches surrounding the Richmond Nature Park.  As mentioned, there were only two ditches with permanent water in 2005. All of the other ditches were seasonal with water periodically or consistently present in the fall, winter and spring. Thus, species may periodically migrate to the study area ditches during wet periods, but without year-round habitat, be unable to survive.

Seasonality of Surveys and Climatic Variation

The seasonality of surveys may have also played a role in the species caught during the trapping period.  Trapping was conducted in the summer and late fall. Some species may be more abundant at other times of year. For example, the probability of the presence of juvenile salmonids may be greatest in the spring after emergence. 

Moreover, the presence, persistence and depth of water in the ditches around the study properties throughout each year is influenced by the weather. Had the fish surveys been conducted in another year with different availability of aquatic habitat, they may have yielded different results. Surveys conducted over several years would create a more representative picture of aquatic habitats in the bog.