# Presentation: 717675

## Slide 1

## Canadian Eel Subpopulations 

**Canadian Eel Subpopulations **
**in the North American Context**

**Prepared by a subcommittee of the **
**Canadian Eel Science Working Group**
** ****for the COSEWIC Status Review **

**David Cairns, John Casselman, Val****érie Tremblay, **
**François Caron, and Nick Mandrak**

## Slide 3

## Table 1. Mean discharge and mean annual landings (1970 - 1989) by region for the American eel continental range in Canada and the United States

**	****	****Mean discharge****	****Mean annual **
**	****Region****	****(m****3**** sec****-1****)****	****landings (t)****	**

** **
**a**** The Mississippi Basin is considered to include the Missouri Basin**

**Ontario portion of FEA1****	****	****123**
**Quebec portion of FEA1****	****	****431**
**FEA1 Total****	****	****554**
**St. Lawrence River Basin (includes****	****16,800****	****456****	**
**     ****FEA1, western FEA2, and U.S. **
**     ****drainage to the St. Lawrence**
**FEA2, FEA3, FEA4, FEA5****	****16,092****	****466**
**U.S. Eastern Seaboard****	****11,186****	****1,076**
**Mississippi Basin****a****	****18,434****	****0**
**American eel range not including ****	****44,978****	****2.096**
**     ****Mississippi Basin**
**American eel range including****	****62,512****	****2.096**
**     ****Mississippi Basin**

## Table 2. Relative contribution of American eel rearing regions to total egg production, based on the assumption that production of silver eels, by number, is proportional to mean freshwater discharge. For purposes of calculation, silver eel production in the U.S. eastern seaboard is arbitrarily set at 1,000.

**	****	****	****	****Excluding**** Mississippi Basin****a****	****	****	****Including**** Mississippi Basin**
**	****	****	****	**** ****	****	**
**	****	****Female****	****	****Silver eels (N)****	****Eggs****	****% of****	****            Silver eels (N)****	****Eggs****	****% of**
**	****	****silver eels****b****	****	****	****	**** produced ****	****total egg****	****	****	****produced****	****total egg**
**	****Region****	****(%)****	****Total****	****	****Females****	**** (millions)****c**** ****	****production****	****Total****	****Females****	****(millions)****c****	****production**

**St. Lawrence****	****100****	****1,502****	****1,502****	****20,025****	****59.2****	****1,502****	****1,502****	****20,025****	****48.8**
**  ****River Basin**
**FEA2, FEA3****	****97.8****	****1,439****	****1,407****	****9,426****	****27.9****	****1,439****	****1,407****	****9,426****	****23.0**
**  ****FEA4. FEA5**
**U.S. Eastern****	****65.5****	****1,000****	****655****	****4,389****	****13.0****	****1,000****	****655****	****4,389****	****10.7**
**   ****Seabpard**
**Mississippi****	****65.5****	****0****	****0****	****0****	****0****	****1,648****	****1,079****	****7,232****	****17.6**
**   ****Basin**
**	****Total****	****	****3,940****	****3,564****	****33,840****	****100.0****	****5,588****	****4,643****	****41,072****	****100.0****	**

**a**** ****	****Mississippi Basin considered to include Missouri Basin**
**b**** ****	****From regional means of sex ratio data compiled by Nilo and Fortin (3001). Per cent female in Mississippi ****	****Basin, where no data are available, is assumed to be the same as U.S. eastern seaboard**** **
**c****	****Fecundity for St. Lawrence River is mean of two measurements of eels from FEA1 (14.5, 13.3 million) and one ****	****from western FEA 2 (13.3 million; Tremblay 2004). Fecundity elsewhere is mean of two measurements from ****	****Gulf of St. Lawrence (6.5 and 6.9 million; Tremblay 2004)**

## Table 3. Migration periods, mean length, and age of female silver eels exiting Canadian freshwater systems.

**	****	****	****Migration****	****	****Length**
**	****Site****	****FEA****a****	****period****	****N****	****(mm)****	****Age****	****Reference**

**Upper St. Lawrence R.,****	****1****	****Jun-Oct****	****200****	****915****	****20****	****Casselman 2003**
**	****Lake St. Francis, vicinity ****	****	****	****53****	****976****	****	****McGrath et al. 2003**
**	****of Moses-Saunders and****	****	****	****30****	****1,001****	****21****	****Tremblay 2004**
**	****Iroquois dam**
**Richelieu R.****	****1****	****Jun-Oct****	****494****	****1,019****	****	****Dumont et al. 1998**
**St. Lawrence estuary****	****1****	****Sep-Oct****	****474****	****840****	****	****Couillad et al. 1997**
**	****	****	****	****4,529****	****853****	****	****Verreault et al. 2003**
**	****	****	****	****30****	****837****	****20****	****Tremblay 2004**
**Sud-Ouest Rivière****	****2****	****Aug-Nov****	****107****	****1,026****	****21****	****Verreault 2002**
**	****(S. shore of St. Lawrence)****	****	****	****30****	****1,043****	****23****	****Tremblay 2004**
**Rivi****è****re aux Pins****	****2****	****	****100****	****600****	****	****Couillard et al. 1997**
**Petite Trinit****é**** Rivière****	****2****	****Aug-Oct****	****424****	****650****	****17****	****Fournier & Caron 2005**
**	****(N. shore or St. Lawrence****	****	****	****30****	****679****	****20****	****Tremblay 2004**
**Long Pond, PEI****	****3****	****Aug-Oct****	****30****	****693****	****20****	****Tremblay 2004**
**Margaree Rivière, NS****	****3****	****Sep****	****319****	****642 ****	****	****Cairns, unpub.**
**Topsail and Indian ponds,****	****4****	****Aug-Oct****	****92****	****694****	****12****	****Gray & Andrews 1971**
**	****Salmon R., Burnt Berry Brook****	**
**	****Topsail Barachois, NF**
**LaHave Rivière, NS****	****3****	****Aug-Nov****	****346****	****611****	****19****	****Jessop 1987****	**

**a****	****Freshwater Ecological Areas: 1 – Great Lakes, western St. Lawrence; 2 – eastern St. Lawrence; 3 –  Maritimes; 4 – ****	****Atlantic islands**

## Table 4. Relative contributions of American eel rearing regions to total egg production, based on the assumption that production of silver eels, by weight, is proportional to mean landings for 1970-1989. For purposes of calculation, silver eel production in the U.S. eastern seaboard is arbitrarily set at 1,000 tonnes.

**	****	****Proportional****	****Relative**
**	****	****tonnage of****	****proportion****	**
**	****	****of silver eels****	****of eggs**
**	****Region****	****produced****	****produced (%)**

**Ontario portion of FEA1****	****114****	****5.9**
**Quebec portion of FEA1****	****401****	****20.6**
**FEA1 total****	****515****	****26.4**
**FEA2, FEA3, FEA4, FEA5****	****433****	****22.2**
**U.S. eastern seaboard****	****1,000****	****51.3**
**	****Total****	****1,947****	****100.0**

## Table 5. Mean values of major long-term American eel abundance indices in an early period compared with 1999-2003.

**	****	****	****	****	**
**	****	****	****Early period****	**** Recent period**
**	****	****	****	****	**** ****1999 – 2003 **
**	****Abundance Index****	****Years****	****	****Mean****	****Mean****	****% change****	**

**Landings, ON (t) (FEA1)****	****1970-1977****	****119.32****	****20.84****	****-82.5**
**Silver eel landings, QC (t)****	****1970-1977****	****361.61****	****141.46****	****-60.9**
**	****(FEA1)**
**Landings, FEA 1(t)****	****1970-1977****	****503.67****	****192.98****	****-61.7**
**Landings, FEA3, FEA4, FEA5 (t)****a****	****1970-1977****	****512.83****	****352.24****	****-31.3**
**Landings, US (t)****	****1970-1977****	****1,057.06****	****400.38****	****-62.1**
**Moses-Saunders ladder, peak ****	****1974-1977****	****13,178.18****	****38.42****	****-99.7**
**	**** ****period index (FEA1)**
**Bay of Quinte trawl index (FEA1)****	****1972-1977****	****1.40****	****0.03****	****-97.9**
**St. Nicholas fall captures (FEA1)****	****1971-1977****	****271.29****	****283.40****	****4.5**
**Restigouche electrofishing****	****1972-1977****	****0.48****	****0.67****	****38.5**
**	****densities (FEA3)**
**Miramichi electrofishing****	****1952-1977****	****0.85****	****0.43****	****-49.0**
**	****densities (FEA3)**
**Margaree electrofishing****	****1957-1977****	****3.03****	****0.31****	****-89.6**
**	****densities (FEA3)**

## Slide 9