In this study, Target strength for multi-frequency (38 kHz, 70 kHz, 120 kHz and 200 kHz) of chub mackerel (Scomber japonicus) was estimated using by the KRM model. The body shape of the Chub mackerel was described by an X-ray system and the body length of 20 individuals ranged from 16 cm to 28 cm. The swimbladder tilt angle ranged between – 8 and – 14°, the maximum TS value according to the swimming angle of chub mackerel was – 33.0 dB at – 11°. The averaged TScm according to fork length was – 66.02 dB at 38 kHz, – 66.50 dB at 70 kHz, – 66.00 dB at 120 kHz and – 67.35 dB at 200kHz, respectively.

벼에 반점미를 유발하는 흑다리긴노린재 [Paromius exiguus (Distant)]의 온도에 따른 산란 특성을 17.5~35°C 8개 항온조건 광주기 14L:10D에서 조사하고 산란모델 구축을 위한 단위 함수 개발 및 생명표 분석을 수행하였다. 성충 수명은 17.5°C에서 123.8일로 가장 길었고, 32.5°C에서 23.6일로 가장 짧았으며 온도가 올라감에 따라 수명도 짧아졌다. 암컷 한 마리당 총산란수는 30°C에서 585.2개로 가장 많았으며, 17.5°C에서 21.5개로 가장 적었다. 온도에 기반한 산란 모델 개발을 위해 성충노화율, 총산란수, 성충생존율 및 누적산란율 단위모델을 추정하였 다. 총 산란수(r2 = 0.83~0.85)를 제외한 3개의 단위모델 모두에서 높은 수준의 모델 적합성을 보였다(r2 = 0.92~0.98). 온도에 따른 흑다리긴노 린재 생명표 매개변수들을 추정하였다. 순증가율(R0)은 30°C에서 118.21로 가장 높았다. 평균 세대기간(T)은 32.5°C에서 32.99일로 가장 짧았 으며, 개체군 배수기간(Dt)은 30°C에서 5.69일로 가장 짧았다. 내적자연증가율(rm)과 기간증가율(λ)은 30°C에서 가장 커 각각 0.122, 1.129였다.

Rockfish was a commercially important fish specie in marine ranching areas in Korea. To estimate density and biomass of rockfish using acoustic method, target strength (TS) information is required on the species. This study measured TS dependence on tilt angle and size on 14 live rockfish individuals at 38, 70, and, 120 kHz by ex-situ measurement (tethered method) and acoustic scattering model (Krichhoff ray mode, KRM). The swimbladdered angle ranged from 18 to 30˚ (mean ± s.d. = 26 ± 4˚ ). The mean TS for all individuals was highest -35.9 dB of tilt angle -17˚ at 38 kHz, -35.4 dB of tilt angle -25˚ at 70 kHz, and -34.9 dB of tilt angle -22˚ at 120 kHz. The ex-situ TS-total length (TL, cm) relationships were TS38kHz = 20log10(TL) - 67.1, TS70kHz = 20log10(TL) - 68.6, and TS120kHz = 20log10(TL) - 69.9, respectively. The model TS-total length (TL, cm) relationships were TS38kHz = 20log10(TL) - 66.4, TS70kHz = 20log10(TL) - 67.0, TS120kHz = 20log10(TL) - 67.0. The two measurements between the ex-situ TS and KRM model for TS-tilt angle and fish size were found to be significantly correlated.

벼 반점미를 유발하는 흑다리긴노린재 [Paromius exiguus (Distant)] 성충의 산란 및 수명을 다양한 항온조건 (17.5, 20, 22.5, 25, 27.5, 30, 32.5, 37.5±1℃, RH = 20-30%, L:D = 14:10)에서 조사, 분석하고 산란 관련 모델들의 매개변수들을 추정하였다. 흑다리긴노린재 성충의 평균 수명은 17.5℃에서 82.0일로 가장 길었고, 온도가 올라감에 따라 짧아져 35℃에서는 평균 24.4일 생존하였다. 조사된 모든 온도 조건에서 산란 가능하였으며 평균 산란수는 25℃에서 455.1개로 가장 많았고 17.5℃에서 150.6개로 가장 적었다. 추정된 성충발육율 함수, 생존율 함수, 누적산란완료 함수는 비교적 높은 모형 적합성과 통계적 유의성을 보여주었다.

Yield per recruit model is the most popular method for fisheries stock assessment. However, stock assessment using yield per recruit model can lead to recruitment overfishing as this model only considers the maximum yield per recruit without spawning biomass for reproduction. For this reason, spawning biomass per recruit model which reveals variations of spawning stock biomass per fishing mortality (F) and age at first capture (tc) is considered as more proper method for stock assessment. There are mainly two methods for spawning biomass per recruit model known as age specific selectivity method and knife– edged selectivity method. In the knife–edged selectivity method, the spawning biomass per recruit has been often calculated using biomass per recruit value by multiplying the maturity ratio of the recruited age. But the maturity ratio in the previous method was not considered properly in previous studies. Therefore, a new method of the knife–edged selectivity model was suggested in this study using a weighted average of the maturity ratio for ages from the first capture to the lifespan. The optimum fishing mortality in terms of F35% which was obtained from the new method was compared to the old method for small yellow croaker stock in Korea. The value of F35% using the new knife–edged selectivity model was 0.302/year and the value using the old model was 0.349/year. However, the value of F35% using the age specific selectivity model was estimated as 0.320/year which was closer to the value from the new knife–edged selectivity model.

This study was focused on acoustic scattering characteristics of jack mackerel (Trachurus japonicus) at frequency 38, 70, and 120 kHz by Kirchhoff-ray mode (KRM) model. The body length (BL) of 16 individuals ranged in 12.2~22.0 cm (mean±S.D.: 17.8±3.2 cm) and the swimbladder length ranged in 4.2~8.6 cm (mean±S.D.: 6.6±1.6 cm) and the swimbladder cross section ranged in 1.7~6.6 cm2 (mean±S.D.: 3.8±1.6 cm2). This result shows that results correlate well between the BL and the length and cross section of swimbladder. The swimbladder angle ranged in 7~12°and the maximum TS values ranged in –16~–5°at tilt angle. The averaged TS-to-BL relationship were TS38kHz=20log10BL-65.33 (R2=0.66), TS70kHz=20log10BL-65.90 (R2=0.67), and TS120kHz=20log10BL-66.65 (R2=0.65). These results can be used fundamental data in order to estimate distribution and biomass of jack mackerel by using hydro-acoustic method.

Acoustic target strength (TS) measurement and theoretical acoustic scattering models were applied to estimate the TS for assessing the fish biomass. TS measurement was made of ex situ sailfin sandfish Arctoscopus japonicus at 70 and 120 kHz, and then compared to backscatter model prediction. The live sandfish was tethered in seawater using monofilament lines. Measurements were made versus incidence angle, −50° to 50° relative to dorsal aspect directions. Distorted wave Born approximation (DWBA) model was used to calculated TS pattern. The TS values of sandfish (body length: 16.2 cm) at 70 and 120 kHz were ‒66.94 dB and ‒64.45 dB, respectively, and were about 20 dB lower than TS of other fishes in Korea waters. These TS levels were distributed within the range of the theoretical TS. Ex situ measurement and theoretical TS may be applied to improve acoustical detection and biomass estimation of the sandfish, and is necessary to measure with various lengths.

Podisus maculiventris (Say) (Hemiptera: Pentatomidae)는 국내에서 기록되어 있지 않은 종이나, 전 세계적으로 8개과 75종 이상의 경제적으로 중요한 해충을 포식하는 천적으로 알려져 있다. 본 연구는 상기 천적에 대한 국내 도입가능성 및 대량 사육조건 탐색을 위하여 다섯 가지 변온조건으로 설정된 유리 온실에서 성충의 산란 및 수명을 조사, 분석하였다. 성충의 평균 수명은 24℃ 설정 온실에서 38.6일로 가장 길었고, 32℃ 설정 온실에서 17.3일로 가장 짧았다. 산란은 모든 변온 조건에서 가능하였으며 암컷 당 산란 수는 24℃ 설정 온실에서 113.1개로 가장 많았고, 16℃ 설정 온실에서 17.2개로 가장 적었다. 추정된 성충발육율 함수, 생존율 함수, 누적산란완료 함수는 비교적 높은 모형 적합성과 통계적 유의성을 보여주었다. 개발된 함수와 상용 프로그램을 이용하여 산란 모델을 구축하고 시뮬레이션 한 결과 평균온도 25℃에서 성충은 2일째부터 산란하기 시작하여 11일째 가장 많은 수를 산란하였으며, 17일째 산란이 종료되었다. 이상의 결과들은 변온 조건에서 Podisus maculiventris의 개체군 밀도 변동을 이해하는 기초 자료로 또한 대량 사육 조건 탐색을 위한 기반 자료로 활용할 수 있을 것으로 기대 된다.

Acoustical backscattering characteristics of Japanese anchovy can be estimated by Kirchhoffray mode model (KRM model) due to estimate exact body and swim-bladder shape of the fish, the samples were rapidly frozen by dry-ice and alcohol. X-ray photos for ventral and lateral direction for 6 samples were taken and the 3D coordinates of the body swim-bladder were estimated by digitizing from the photos. The angles between the axis of body and swim-bladder were about 9˚ at 38kHz and 7˚ at 120kHz, 200kHz. General formula of TS and BL estimated were 〈 TS38kHz 〉=20logBL-67.3, 〈 TS120kHz 〉=20logBL-66.6, 〈 TS200kHz 〉=20logBL-67.0. As a result, we confirmed KRM model is very useful to estimate TS (Target Strength) for design of experiment and it also can be applied to estimate the abundance of Japanese anchovy distributed by 2 frequency difference method in the survey area.